Too late to the thread but here is my thought on manufacture space reservation.
I don't see any point in it from game strategy perspective. Fine, each item requires some
extra workshop space. What normal player does? Build some extra workshop or hire less technicians per workshop reserving this extra space. One can build +10 extra workshops and don't bother with queueing manufactures. What does it really equates to? Extra cost of workshop construction and maintenance + extra tile used at base. Nothing freaking else!!! No strategic decision here as there is no other option.
If this is an only intention then just set reserved space for all manufactures at 0 and increase workshop cost/maintenance some for the equal outcome. Equally, all manufacture efforts can be proportionally increased for about the same outcome.
What is that fixed extra space anyway? Why is it
fixed Is it a reserved space for "assembly line" or something? This does not make sense too. What, one engineer needs one "engineer cubicle" to work in + 20 space for assembly line to assemble a tank? Why then a thousand engineers need thousand cubicles but still same 20 space for a single assembly line? How they manage to fit all there? How they manage to produce it
faster with same single assembly line? If anything, it should be proportional to number of engineers (every one needs a space to work would it be a personal space or
part of assembly line) and the rest of materials can reside in storage as they should.
If you think this way, the same concept can be transferred to research. Indeed, each scientist need a place to reside + some space where actual thing is getting researched. Yet, designers wisely factored this extra space into personal scientist space. More scientists require more laboratory space = build more laboratories to hire more scientists. Simple and intuitive. We should do the same with manufacture.