I often go through this:

https://wiki.archlinux.org/title/Pacman/Tips_and_tricks

You can quickly remove all unused packages with this command: (from the article above)

pacman -Qdtq | pacman -Rns -

My arch install is many years old, I don’t feel the need to re-install.

I just looked up the initial release, it was in August 2001. I don’t remember the first time I used it, but it was probably 20 years ago. Still remains my favourite for the reasons you mentioned.