I wouldn't mind researching multiple techs at once sometimes as long as I could go back to researching one tech faster later on. It really depends on the situation, There were times I wanted to research sensors, research, and economics at once. There were tunes where I needed to research farming, terraforming, life support, miniturization, engines, and missiles at the same time, so I can feel them when they want this ability.
I like the idea, but, IMHO, that would require partial, of not complete redone of research system. Well, in simplest solution it won't - if researching techs in parallel will require same amount of time, as researching them sequentially or individually, then parallel study will give same results as queue study - simple reduce of micro control. So, instead of jumping into tech page every turn you would go there from time to time.
But this wouldn't be real parallel study. To make it real, we need to have certain threshold on techs, and it should be impossible to study tech faster, than that threshold would allow, no matter how many scientists will be working on it. Should all tech be provided with that threshold, it simply wouldn't be wise to reorient your research cap on one tech. Also, to supplement this program, we could study our tech at once, all of them. Certain reallocation of workers should be there, allowing to boost research progress, but again, there should be threshold of workers too, to prevent "overcrowding". Or, instead of workers threshold, there could be inverted progress scale: say 10 scientists will discover tech in 200 days. 20 scientists will discover tech in 100 days (if we keep this part of scale flat), but 30 scientists won't uncover tech in 50 days, or instantly
, all they could do, is to reduce time to just 90 days. 40 scientists will reduce time will be able to decrease time to 84 days, adding more scientists won't have any positive effect. Maybe only negative.
In this system, picking just one tech will be useless, and after certain point there will be no use to build more research stations, because there are no more room to maneuver there - you'll simply hit the ceiling of your research potential, even including possible boost from temporary increase of numbers of active workers on the project. In this case, every additional research station could be used for commercial use - allowing you to lend your research cap for other races.
To an extent this system is somewhat similar to SoaSE research system, with two main differences - SoaSE system had sequential tech pick-up, and research times had fixed values. Yet there was cap of research stations, allowing us to build different structures.
My question is how come on earth that when technology is getting better, and the world get's bigger the fleets get smaller not bigger...
Although this part is not for me, I think there is something I'd like to discuss. On Earth we have constrains of space. That's why European trucks are generally shorter, and that's why they have cabs over engines, and their sleeper sections are smaller than those of their counterparts in US - you'll have problems fitting large US truck on some roads in EU, they aren't designed for trucks that big. That's why some trucks manufacturers offer specialized chassis, with reduce mass, lowered height, smaller fuel tanks, etc - simply to allow you to haul more cargo for same running costs. Yes, you lose in versatility, but for specialized companies or freights this could be saver.
Certain miniaturization comes from fees and taxes inflicted on us by our governments - smaller vehicle will be lighter, thus requiring weaker engine, consuming less fuel, thus offering lower taxes. For people living in cities and prefering to haul their butts in comfort of personal car, instead of joys of sweaty and smelly public transport, those microcars "fitting between two trucks without them noticing" could be solution. Not sure for northern countries with snowy winters and cold temperatures.
Anyway, every process has its limits. For example, tanks see little action because of their price, it's almost on par with helicopters, because of those electronics we now stuff into. Yet if helicopter require decent AA, and it is usually expensive, to be countered with, tanks can be stopped with mines, and comparison of prices between mines and tanks... You know, not in tanks favour. Even RPG/AT weapon prices are still lower, even if we take 1 tank= 9 RPG wielders ratio. And don't forget their fuel appetite - smaller, of course, than thirstiness of helicopters, but much greater than other vehicles. So first limit is price.
Second limit is physical limitations. For example, in tanks with loader in crew you have to give him around 160 cm of height between turret's floor and ceiling, to allow loader operate normally. Because of that you can't make tank lower. And there is another problem - disproportional increase of vehicles' mass depending on which parameter of overall dimension you increase. If you increase tank's lenght for certain unit, then tank mass will increase on 1 "point". Should you increase tank's width, then tank's mass will increase on 3 "points", and should you increase tank's height - tank's mass will increase on 9 points. So it's not effective to increase tank's height without good reason. Yet there may be no choice. For same reason there is limit of armour protection, and armament power. The former will require more powerful engine, thus resulting in fuel consumption, and the latter may require increase in overall dimensions.
And that's third limit - the bigger it is, the more resources it needs to be created. Yet sometimes there are no options to but build something big, if you want to install something big. So here we will have same problems aircraft engineers met - to increase range or speed, you need either bigger tanks, resulting in increased size and mass, and thus you need bigger engine, which consimes more fuel and eat the very same space you could give to fuel tanks, to increase range. And don't forget about protection you should give to elements of the aircraft, to make it less vulnerable.
Of course, in space we may ignore needs of aerodynamics, but what about ballistic? Should we give our hull proper angles to increase chances of ricochets, thus reducing overall thickness of armour plates, thus reducing amount of resources needed to build this ship, and either to make ships smaller, or to use inner space for something useful.
I'm not space engineer, so I can't provide any calculations on required strength of construction, to prevent ship from split up during extensive maneuvers or during combat, not sure if reverse submarine engineering would help. 
That's actually my point where on the game on my home planet it would take three weeks. For the most part our industry matches our needs. If we don't need thousands of ships each day we won't be able to make them. Our advancement usually matches our ability to make ships. In a future we won't be able to run off thousands of ships per planet each day, so people should stop saying we would. There will not be an ability to make ships if don't need to.
How many Liberty series transports were manufactured daily in US during WWII? Almost one in a day? Even if one ship required what, 24 days do be made? How many planes, tanks? There was need, and we should be well damn ready to produce as much as our forces need, not as much as industry can, otherwise we'll meet same fate as Germany did.
Soviet "teenager", from vocational school, could weld eight hulls of T-34 in a day. Eight, highly skilled German welders required two days to weld hull of just one Tiger tank. Maybe one on one Tiger was oustanding, but what about one on sixteen? Don't like T-34, replace it with Sherman. Maybe that tank wasn't as good in duels with Panthers, but there been a lot more of Shermans, they were there when troops needed them, and in quantities generals needed them, with every piece of logistical chain, excluding practically any problems with maintenance and supply.
Germans had no recovery unit, capable to tow Tiger tank - they had to use another Tiger (or two), or several Sd.Kfz.9 vehicles. And don't forget, they had specialized railroad platform to ferry Tigers, and to load Tiger on that platform you had to replace caterpillars on them (and upon unloading you had to put "combat treads" again, do I need to tell it wasn't fast job? If that's not enough, they had no tankers to fuel tanks, only jerry cans. And Tiger needed 27 of them. Even then, operational range was under 100 km (off road). I doubt I need to say anything about Tiger's wonderful suspension, repairability of which was very low, or, at least, time consuming.
That's the example of industry capable to produce as much as it could, not as much as were needed. Also it is example of bad logistics and manufactureability. Strategical planning also.
Rather low manufacturing rates aren't problem when you plan to use things you built when you have the initiative. But when you don't...
Never thought this was a big deal as far as waste. I kind of want to see multiple techs, but I think there are better ideas as far as tech improvement. I do like the Que idea.
If you accumulate all that waste we had in GC1, and, to lesser extent, GC2, you could be quite shocked of amount of your Research cap went somewhere where it shouldn't.
I was reading this list and I found androshalforc's suggestion that existing buildings give bonuses to researching technologies associated with them, i.e. farms improve farming and terraforming, etc.
This is, to an extent, similar to Hearts of Iron system, when something built and used practically gave bonus to theory. In return, theory gave bonus to practice. So they kept each other moving.