A few examples for me:
- From a "pull request / files" view like this (https://github.com/google/protobuf/pull/1191/files), when I want to view a whole file, I always want to click on the filename. But the filename isn't a link: you have to look at the right side and click the button that is generically named "View" (View what?).
- At the top level of a repo (ie https://github.com/google/protobuf), you can click "X commits" to view the list of commits. But when you go into a subdirectory (ie. https://github.com/google/protobuf/tree/master/benchmarks) the "commits" link disappears, and to view the commits in that directory you have to look on the right side instead for a button that says "History".
- continuing from my last point, if you view an individual file, (ie. https://github.com/google/protobuf/blob/master/benchmarks/Pr...), the "History" link is in yet another place! So between the top level, a subdirectory, and a file, the link to view history is in three different places. I don't follow these links quite often enough that it becomes automatic, so it slows me down every time.
The people who is it once every week or two, like me, get lost each time. It's always a hunt when I want to figure out how to do something, even if I know I've done it before.