1500 rpm=25rps=12 1/2 ignition sparks per second= 0.08 second per spark
3000 rpm=50 rps=25 ignition sparks per second = 0.04 second per spark
6000 rpm =100rps=50 ignition sparks per second=0.02 second per spark
think about where your piston is at in the cycle dealing with TIME ( a constant in physics ) in relation to your degrees of timing according to crank rotation------------
Keep that too much advance at the lower rpm levels for the sake of cruising economy is probably more destructive when you moderately accel (no downshift) to pass or climb a hill than if you downshift and rev it up---cutting the time wave before top for that dreadful knock-----------
And if I opened a box of pistons that said limit timing-----------------