I've gone both ways on the "3-day call rule," and had varying results. Calling her a week later, way too late, even if you have a valid excuse (I actually WAS away for a week without a phone because of work). On the other hand, calling her the next afternoon, maybe too early, unless it's because you left your cellphone on her bedside table (oops, though I guess, technically, I was calling myself). Three days...well, that just never happens. That's usually a Monday or a Tuesday, and I work both those days.

But, that's just me. YMMV