Complexity is usually quadratic or factorial. Only a tiny number of systems are logarithmic. 20% reduction in parts can often be a 40-70% reduction in cognitive load.

But the funny thing with fractions is that if go above a threshold and come back from the brink, the path back is a smaller number than the path out. So if you go from 8 to 10 steps that's 25% worse and if you undo that bad decision you are getting 20% better. So you want to be careful to compare sustainable to unsustainable and not the other way around, if you follow me.