Upon first glance of the SPT rulebook, I can find no rule relieving you of the obligation to take breaks. That is NOT to say its not there; I just cant find it. I am familiar though, with that rule in other rulebook. HOWEVER - an hour and 45 minutes running time for any theatrical presentation is a ... mouthful. Perhaps while still in rehearsal, the Director can find an appropriate place to take a very well-deserved break. Technical run-throughs, with all the bells and whistles - IF YOU DON'T STOP, can be run without a break, regardless of the running time. If the run-through is stopped FOR ANY REASIN, IMHO, that constitutes the need for a break.