I think it needs to be said that if you are of the mindset that says "I just called her once. I now have to wait 2.58 days before I can call again or she will think I'm desperate", than calling once is probably too often.
Why are you wasting time filling your mind with the number of times you call a girl? Remember, you're supposed to have several girls to choose from; if the first one is not available, call the next girl.
For example:
Last night, I got three phone numbers: Raven, Kristen and Margie. Each have their own unique charms and I'll be just as pleased to spend time with any or none of them. I place them in a queue, First in - First out rotation.
Tomorrow will be Friday, so I'll wait until Sunday and ask them to join me for an activity on Tuesday, Wednesday, Thursday, respectively. If Raven is not available (not home, doesn't want to, conflicting schedules, whatever) I'll just call Kristen for the next available date in my calendar. And so on. If none are available, I'll try to reassess the signs they gave me to make me feel they were interested in me in the first place. Then I'll go back out and see what else happens.
Remember, there are no rules, everybody is different!