I think the production times in this game is nuts for various items, but that is a balance issue I won't discuss. What I want to discuss is how to calculate the times. In my experience you spend plenty of time setting up for a certain fabrication project, but once set up you could crank out units with ease. Happens all the time in the local machining shops, some only take projects with a certain number of items minimum to be produced.
Maybe calculate times for fabrication of stuff, say a laser rifle like the following:
W = amount of item on queue for production
X = total time to make for entire run
Y = shop setup time
Z = time to produce each item after shop setup
X = Y + (Z*W)
