I think it’s a good exercise going back and finding old music you made and with knowledge you’ve gained since that time, see what you can do to change the music. I went back to a track I made two years ago and saw how much wasn’t gain staged and not mixed properly and how much work needed to be done. For example, I needed a fatter kick drum to fill the low end/sub region and it made the mix sound instantly better. Great technical practice but also rewarding!