The laptop started with Windows 7 (the best one btw). Switch to Ubuntu was done years later when I handed it over to my parents.

You are right about the Ubuntu upgrades though. Over these years I'd just randomly press update to get out of EoL'd versions when I was around. I think I just went over 4 major versions in a few hours. It just downloaded, installed and restarted without any problems. One outlier was an issue with nvidia driver packages after update, for which I had to consult google.