Well I'm not talking about forcing slaves to work, but rather wondering why weren't living conditions improved for those slaves?
Better beds, foods, regular breaks, no random executions by Pitt Raiders, etc.
Because there wasn't the extra time to waste- keeping workforce numbers up at all was constantly feeding a meat grinder as you had losses to Trog attacks, losses to slaves becoming Trogs themselves, plus the (minor in comparison) random execution by sadistic Pitt Raiders.
My point is it took every bit of manpower Ashur could come up just to "break even," and couldn't spare the labor. "Hey, to hell with Ronto's latest scouting parties, let's shut the Ammo Presses down and build some nice clean dorms for the sla...er, workers!"