Ignition Timing Education

[olddog]

I understand that there is a lag time between when the coil pumps out a voltage to the plug and when the air/fuel lights.

I also understand that the air/fuel burns and hopefully does not detonate all at once. Furthermore that the goal is to get enough fuel burned at the right time to maximize the pressure in the cylinder at the right time to get the most force to the crank taking into account the rod, piston, and crank angles.

But here is what I have never understood. Why is it that the timing is advanced up to somewhere up around 3000 rpm give or take, and then no matter how many rpms from that point on up, the timing stays the same?

For example say 20 deg at 2500 rpm WOT gives the most HP and then 35 deg at 3500 rpm WOT gives the most HP, why would 35 deg at 6000 rpm give the most HP? Intuitively it seems to me that 6000 rpm would require more advance like 45 or 50 deg maybe even 60 deg.

I hope someone can educate me on this.