Continuing ignition timing debate from the 416 thread.

Still having a hard time wrapping my head around this. You can't use a sweep test on a dyno set an ignition curve because it sweeps too fast and the power changes you see won't be accurate enough to determine a curve. But, you can use a dyno in a sweep test to determine if you made any gains when you change the curve?
I see you hit the agree but as I read that it looks like a contradiction.