Interestingly, just the other day I heard a variant of the same rule used in the contract business. The idea is that every year you ask yourself what 15% of your business you most can do without (either the lowest profit or the biggest headache) and then get rid of it. That gives you room to grow and try something new next year.

I wonder if successive applications of the “15% contractor rule” (in a gaming context) would lead to some sort of lean, mean uber-game? Unlike swapping out 20% to avoid getting into a rut, you’d be paring off the 15% you liked the least.

Looking at it another way, the 15% rule is just a way of quantifying the process of improving your game over time — see what works and what doesn’t; make changes; try them; repeat.