Brando...that's different. From your original post, it sounded like you called her yesterday and she hasn't called you back in a 24 hour span. Sorry if I misunderstood...yeah over a week even for a mundane isssue is a stretch.
Mark...its a fact dependent situation. If you have a customer that you know doesn't need anything urgent, then I'd bet you don't drop everything and call them in 6 minutes.
Personally, I try to return every call no matter how trivial, the same day....it may be 9:00 pm, but I try. On the ones who are a pain in the ass, I'll call back at 7:00a.m