I really like understanding how stuff work, even when there is no problem. So can the experts explain these observations?
I can run this commend:
sudo apt-get update && sudo apt-get upgrade -y
twice in a day, and the number of headers can be completely different. It can go from 9 to 25, even if nothing has happened between.
I can run Ubuntu Software Updater, then immediately after run that same CLI. The Updater will say I am up to date, while the CLI downloads stuff, sometimes a lot. Aren’t they doing the same thing?
Is it wise or unnecessary to run autoclean and/or autoremove after an update or upgrade? It seems that most of the time, I am removing headers and a few lib files, no more.
I can’t give you an exact expert answer, but I can assure you that Linux is all about you. You decide. Especially in cases like:
This is all up to you. I rarely use that function, others might find it very useful, depending in their respective needs and wishes. Neither is wise, nor unnecessary.
I would comment on the other questions, as well, but that would be just speculation, so I let it be.
I’m no expert, but like yourself, prefer to update my system, and do use autoclean, autoremove and clean on each new session. More habit forming since I started using Debian a few years back.
I was of the opinion that apt-get had been deprecated and replaced with apt.
sudo apt update && sudo apt upgrade -y
Other systems have a GUI update icon located in the panel system tray, that open the update manager, i.e this appears to be Gnome Software Manager in Ubuntu. I prefer Synaptic Package Manager.
Mine is out habit due my current Debian Xfce desktop does not have a builtin GUI like Ubuntu. I 'd say horses for horses.