TL:DR: Add the code in this Gist to an mu-plugin.

By default WordPress only shows 20 items per page on admin screens. That’s way too low to be convenient, so I always update it to a more reasonable number, like 120. I end up having to do that on every screen on every site I work with, though, which is tedious.

So I wrote some code to automatically show 120 items on all screens. It can be installed by adding it to the wp-content/mu-plugins folder.