From: Freelance Traveller

> In "classical" Traveller (i.e., the Third Imperium and 'compatible'
> settings), ships are allocated engineering space, and on deck plans the
> various 'drives' are roughed in as very irregular shapes. However, with
> the sort of miniaturization of electronic components that we can do
> even today, about the only thing that causes irregular shape is
> _mechanical_ connection or interfacing.

Or mechanical objects; a power plant may well have a very specific shape. Of course, it should be the same on all ships, and there's a separate problem that they may be located behind bulkheads -- while the rules don't specify one way or another, there is a good chance that all high-energy components are unsafe to be near while in operation, in which case 'engineering' may look like a workstation with some screens, plus some closed doors and a bunch of storage space.