Jim... I'm 99% certain I know what your answer is going to be here, but what the hell. Maybe someone else can learn from the Question.
As the 5/3/1 cycles add up and the weights creep higher and higher towards your actual 1RM on any given exercise, is it wise to slowly drop the amount of assistance work to allow your body to recover better from the more intense PR Sets. I've seen many successful peaking cycles in power lifting work this way (not that this is a peaking program, but the idea remains the same... Drop the fluff and allow the body to recover from the heavy shit)
Month 1-4: BBB 5x10
Month 5: BBB 4x10
Month 6: BBB 3x10
Month 7: BBB 3x8
Month 8: BBB 3x6
At which point you will probably be coming up on a reset or a "5 forward 3 back" kind of situation in my experience.
How say you, Jim? If you like it we can give it a cool name like "Mysteriously Vanishing BBB" or "Where did all my BBB go?" ... Something like that.