Often I don't know what particular repo I'm interested in as a model of good quality overall, I just want to see "where has anyone used function X?". If examples aren't in the library itself, then you have to look for projects that use it, github is the best player in town.

It's funny that we have different experiences - I guess I use more niche libraries than you (or am worse at understanding other people's code)? For more mainstream stuff (javascript questions) I can e.g. go straight to MDN. For questions about the Unity game engine I'll often find good examples in their documentation, but for weirdo game engines random projects on github can be a lifesaver.