@Wade, your working out the arithmetic of shifts from crew sizes has greatly helped me get a sense of the ship’s physical size. Thanks!
@Matsiyan, good point about the multiple roles.
Matsiyan has also touched on the next point I was going to make: since we have been known to run a bridge into action with five or four or, in extreme cases, even three people, it would not be difficult to envisage the 2nd and 3rd shift consisting of Helm, Weapons, SciComms and Engineering, with the highest ranking doubling up as Command. As long as someone is there to press the Red Alert button, the main crew can scramble into action pretty fast.