3 minutes, 3 sets, full body? dang that's a long workout!
I would 'guess' if when a person tests RM's for HST, they might want to test RM on final set? Like if you can do 120x15, but can only do 100 for 3x15 with 2 minutes rest, then 100 would be the 'last workout' of the 15's, not 120, does...