It takes it 2 to 3 days to get through all the packages as is. This could be sped up drastically by maintaining a database of failed outPaths.
I’m just worried that the bot might not have enough checks in place that it submits some nonsense PRs. I think there is some aspect that nixpkgs-update is introducing extra work for maintainers, because it is catching all the updates from hyper-actively updated packages, and I want to keep the overall quality of nixpkgs-update PRs very high so they are easy to merge and to trust that they will be good.
Another reason I like to manually monitor it is that I am usually developing nixpkgs-update and I don’t have much of a test-suite, so if something goes wrong, I like to catch it through manual monitoring. If I work on improving the test suite, I think I’ll feel much more comfortable making it automatically run continuously.