[whpalmer4]

Curt Clifton first pointed it out many years ago, and I've mentioned it in my various discussions of the review feature.

You're simply trying to maximize the least common multiple of the two periods, and if you have two numbers which are relatively prime (they share no factors except 1), you will maximize the least common multiple. If you start both a 7 day cycle and a 17 day cycle today, they will not coincide again for 7*17 = 119 days. Put a start date and a due date on each item so you don't see it until it has been out of sight for some time, and "smear" the start dates across the period. For example, if you've decided that you will use 2, 3, 5, 7, 11, 13 as your various periods, take half of the actions that will have a period of 2 days and set them to start today. The other half you set to start tomorrow. With the tasks that have a 3 day period, you split them into 3 groups, 1 starting today, 1 tomorrow, 1 the day following. What you see as available on any given day will change rather unpredictably, so long as you actually do the items that appear :-)