This is one of my quirks. I keep track of how often I wear my shoes. It started about 6 years ago. I mentally kept a running tab of how many times I wore a pair of boots as I wanted to make sure I got my money's worth out of them. There came a time when I couldn't keep track in my head so I switched to this system. Each Post-It includes the month and year the shoes were purchased and for what amount. Then the running tab. I know. I'm weird.