l = [1,2,3,5,8,13,21,34] <--- this is the list of fibonacci numbers. The probability of a user being on the track of once every l[7] is higher than the probabi

l = [1,2,3,5,8,13,21,34] <--- this is the list of fibonacci numbers. The probability of a user being on the track of once every l[7] is higher than the probability of the user being on track for once every l[0]. Users change tracks on a monthly basis. So if you're on a once every 21 day email cycle for June, you might be on a once every 8 day email cycle for July, although the probability is high that you will stay on the once every 21 day cycle