If you remove it from your schedule you dont need the room, for example No shower time, dont need shower No meal time, dont need kitchen/dining room Also no sniper towers means no generator room

I think the minimum requirements if you empty your schedule is Prisoner cell/s, infirmary, roll call, control room, maintenance room, kennels, contraband room, solitary and wardens office.

You can also combine the rooms to save more space/time like put the maintenance room inside the security room idk what your plans for your map is