The allow_read_errors_with_report option in uproot.dask is convenient not only to understand issues but also to study performance. While the duration seems to always get filled, I see call_time with None values for successful tasks. Unless this would be a performance issue, I believe that always (or optionally, controlled in some manner) filling this value would be useful. I would be particularly interested in using this to calculate instantaneous data rates (as this opens up the possibility to calculate data read by each task, alongside all required time stamps).