Refueling seems easy to do with vanilla interrupts. What does the mod add?

Also, I want to note that you won't be able to edit the schedule if the train is in a group. Also, if any interrupts were set for the train, train.schedule = current_schedule will erase those interrupts.

Try running one of the schedulers that manage your train schedule. If you make programmatic changes to train schedules, all interrupts are deleted (there currently is no API to retrieve / manage those).

If you use standard trains with manually managed schedules and interrupts, you don't need this. It is a programmatic solution for a world without interrupts.

(the other answer is obviously "I needed something like this in a large save porting forward from 1.1". As it took maybe two hours to put this together based on the old 1.1 refueler, it was worth the effort for me. )