"If you set it at 60 minutes I don't think you are going to have a problem with battery, but isn't it a bit scarce? Meaning, if you go to class you 'll have a loud phone for the first 1-59 minutes depending on when the timer will fire."

That's right, but If you make it possible to make that red circle bigger(=cover more area) than it won't be a problem, since our campus is at least half an hour away from the city, I can just select a huge area, by the time I arrive at class It'll be silent. Ofc this may stand as an issue on some use-cases, but better than nothing.