>>16954200
I can't speak for any other companies, but I can for JR. Punctuality is key. Your job, quite literally, depends on it.
There are some JR routes with five second tolerances per stop. They're not a suggestion or a best case scenario. They're a requirement. Every single day, every time you make a stop. They'll tolerate, at most, around two screwups in a six month period. Then you're done. You're also done if someone even suspects you're going to screw up.
I can also assure you the rest of your working life there will be as hostile as the adherence to safety and timetables. Don't miss a signal announcement (they have cameras in cab, they know the exact moment you do), a timetable, a safety sign, a driver inspection, your scheduled break and lunch times, your driver changeover time, company holiday outings, or overtime.