what's a surprising (but impactful) manual process you've encountered?

A fun question today for searchers or successful acquirers - what's a standout example of a process that you discovered in a business you diligenced or purchased that you expected/experienced a big benefit from improving?

We often talk about inefficiencies in older founder-run businesses that a new entrepreneur can fix. What's something you've seen or fixed yourself?

Hoping this can generate some ideas for the community.