Not used to seeing this but one site just stopped at each step of the journey.
As per the code, retry and skip seems to be shown with the value set for debug. Note
Enable Debugging if it is turned on/off on
Administer-> System Settings -> Debugging and Error Handling.
Need to confirm this on another upgrade I do, but for now, it seems retry and skip would show up if debugging is enabled and the upgrade would progress only after Retry button is clicked. So for continuous upgrade, one should have
debug set to