As for the upgrades themselves, only Tech Tool Pro requires a payment (although they have stated that the Big Sur compatible version will be free). Also, if one needs such software for an issue, such software needs to be compatible, especially at the time one needs it. I prefer to wait until such compatibility is there.
Out of curiosity, when was the last time you actually NEEDED to run TTP?
Why the SHOUTING? I am right here, not 10 miles away!
But, to answer your question, I am a cleaning "nut", no matter what it is: our cars, our townhome, the dishes, my computers. Since I run my two SD backups for each machine every Saturday, while I am cleaning my town home, it is not a burden to first run Onyx AND Tech Tool Pro. It just means I have a "as clean as possible" backup/clone.
When that issue with OS 10.15.6 reared its ugly head, I did run TTPro on those just completed SD backups. Nothing found, but better to be safe than sorry.
I am willing to bet that over 75% of folks do little, if any, disk cleanup/maintenance. I actually am doing disk cleanup every day by permanently removing deleted EMails in Thunderbird. It's just second nature to me. And I have consistently seen folks have issues with Apple's Mail program. When I mention permanently removing deleted EMails, they don't have a clue what I am referring to.
