How often should I review my notes? Many years ago I was studying with the Open University. During that time I bought a revision aid. The basic principle was that you wrote out all you knew about a topic immediately after learning it. The note pages were marked so that they could be referenced against a sort of calendar. The idea was that you read through your notes something like the next day, again a week later and again something like 4 weeks later.

I recall that the thinking was that the frequency set coincided with the way your brain moves stuff from short- to long-term memory.

I'm just about to start studying again and I wondered if anyone might know what the frequency for reviewing one's notes might have been.
There are several algorithms for scheduled repetition of information on flash cards. It's possible that the software you liked uses one of these. This Wikipedia article on spaced repetiton discusses Pimsleur's graduated-interval recall and Leitner system, among others. This isn't the easiest topic to search for, but the Wikipedia article calls it "spaced repetition", and includes a list of alternative names. That should help you do further research.