For me, there is no schedule to purge, downsize, or whatever else you want to call it. Most of my shoes are usually purchased second hand. So they sometimes wear out quicker. Plus I find my taste in heels changes from time to time also. I never buy shoes I don't like. But sometimes I'll go through my collection from time to time, i'll find a pair of heels and go, what was I thinking! Plus, my shoe size seems to change from time to time also. So shoes that fit a year ago may not fit now. Or sometimes I just downsize. I'll go through my collection and get rid of shoes that I haven't worn in a really long time.