You are exactly on track!

My statement, "The process is NOT additive" is ambiguous. (I see that it could be read that the "process of creating small dams" is not additive.)

I should have said the erosive energy is NOT additive.

A 90' drop is >>> greater than six 15' drops - even though the math is the same. The physics is not the same.

Any time you can break the water flow chain with a level surface of pooled water, you are reducing your erosion.