it was my first time trying a "cleaning app" from the app store. Is that making things worse?
Hello again Jeff,
It well could be. Apple included automated maintenance routines in macOS starting 20 years ago. They do all the cleaning, temp file management, and even defragging, and in an unobtrusive manner. Third-party cleaning apps interfere with this elegant system and WILL slow hard drives and reduce stability. So will anti-virus software.
Just because something is in the App Store does not mean it is good.
I accumulate a lot of files from school and large photo files so what I do is back everything up and just reformat my iMac.
IMHO, your back-up/reformat scheme is overkill. The Fusion drives seem less forgiving of user manipulation than conventional HDDs or SSDs. I've had no issues with simply trashing unneeded files and then letting the automated maintenance routines take care of any disk fragmentation or temp file accumulation that occurs. And all my Macs are stable. They don't get bad habits until at Death's door.
The maintenance scripts run daily weekly and monthly in the wee hours of the morning, even if the computer is asleep. If the computer is turned off, scripts run in the background at the next startup. Very slick.