My advice... how retention by "cycles" works in Commvault is complicated. It's implemented exactly as documented so I can't say there's anything wrong with it. That being said, it can lead to situations where you expect a backup job to age off but it doesn't.
If you're using both days and cycles, the jobs won't age off until both conditions are satisfied. The extreme (but obviously very common) example would be if you add a backup job and you only back it up a couple times before identifying that you never really needed it backed up. You then decide to turn off backups for it. None of the backup jobs will age off because Commvault will happily try to retain all of the last 4 cycles even when only one cycle was started.
In my environment, I just use retention based on days/weeks/months. For items I want to stop backing up but keep forever, I have a separate storage policy I assign them to and then I do one final full backup. For most items when I stop backing it up I don't need to keep it. Your regulatory requirements may be different than mine but this simple setup has served me well for several years now. Whenever I run low on tapes I know that I can within a few clicks easily identify if I need to buy more or if I have something wrong causing them not to age off. If I was using cycles plus days as a retention period I'd have to run the data retention forecast report and deep dive into those results before coming to an answer.