I help tune an 8 second car with a PG. That car only falls back 50 rpm on the 1-2 shift. Kind of crazy and I'm not sure that is the fastest way down the track but that is how it is set up. You can't even really hear the shift and the data log only shows a small blip when it shifts.

I was originally taught that the engine should fall back from peak power to peak torque on the shift which is about 1500 rpm for most engines. But I think that is now considered "old school". It does make more sense to keep the engine right around peak power as much as possible.