If you properly deload and have a sensible warmup then most of the time it's fine.  Typically it's built into a program, especially when you actively compete. But you are correct, it is 100% stupid to repeat a 1RM over and over.  Obviously it's not a 1RM, it's a single.  And no one should occupy a rack for that long, it takes my partner and I maybe 30min to get through a warmup and 6 working sets.