We have mandatory code reviews for everything, which encourages small, bite-size commits and frequent merges. Majority of the changes goes through with just one

We have mandatory code reviews for everything, which encourages small, bite-size commits and frequent merges. Majority of the changes goes through with just one other person taking a look. But we also specify (and highly encourage) that anyone trying to land a more invasive or complex change should require multiple review approvals. The most demanding "please pile on, we want eyes on this" request I remember was set to require 4 separate approvals.