I think it should be pretty obvious that for instance retry logic should be near the place in the code where the first attempt is made. The best case for gathering all errors in a 'railway' is when they can be handled uniformly. E.g., if we want to not retry things but instead report a descriptive error message to the user. Note that also that most error handling logic that should be near the calling place might also fail in more global ways that are then best handled using the railway/exception pattern.