Catalina I think is more glitchey than normal because of 64 bit issue is one of the more glitchy upgrades, but not as bad as the OS 9 early OS 10 era.
I have not found Catalina to be more glitchy, but because of the mandatory conversion to the APFS file system, the system being moved into its own read only volume, separate from third party apps and anything belonging to the user in another volume altogether, and lots of preferences
etc. being moved deep deep into the bowels of the directory structure, AND the 64 bit issue there has been some (a lot ofâ“) confusion. There are future compatibility issues with some kernel extensions probably coming in Mac OS 10.16 (in anticipation of a conversion to ARM processors instead of Intel? 🤷â€â™‚ï¸) but there aren't many of those. Third party developers are waiting for Apple to finish documenting the new APIs (which will hopefully happen before the 22nd fo this month when they get their hands on the first Developer beta of MacOS 10.16). I'm eager(?) to see what the first public beta of MacOS 10.06 breaks.
REmember Disc Warrior is that still around?... So thing are overall better these days.
Diskwarrior is still around, but they have not caught up with APFS yet. But like TechTool Pro and Drive Genius it is so seldom needed that many (most?) users are no longer keeping it up to date on the premise they will buy it if and when they need it and not before. (Not to mention the disk and file optimization stuff we used to do no longer makes any sense on SSDs and arguably may shorten an SSDs lifespan and even make the data less secure.) There is an entire dictionary of routines we used to do prophylactically that we have forgotten about, as MacOS has become so stable they are pointless.
BTW, Malwwaye Btyes, says to just schedule 1x a day, and additional machines are only $10 year extra...
Whatever, I will stick with my three hour routine as it doesn't hurt anything and has an undetectable effect on performance.