On a side note, the fact that you live in Philadelphia alone is reason enough to carry 24/7. I live just outside of the city, about 20 mins away, and I am planning to carry all the time myself.
The town I live in is relatively safe also but it's only about 5 minutes outside the City of Boston and not even a 20 minute drive away is Dorchester Massachusetts, which has gang shootings just about weekly. My cousin does crime scene cleanup and was called in late last week to clean up after a shooting, while they were there cleaning a few blocks away another shooting occurred. A few weeks before that a car full of innocent girls was shot up during a drive by because one of the girls owed someone money. This is one of the reasons I carry daily, because even though the town I live in is relatively safe, those trigger happy criminals are but a short drive away. So I guess the point I'm trying to make is no matter how safe your town is, nothing is stopping these gang affiliated types from wandering in.