DavidR
13
With the notable exception of winME which seemed to be a total lash up and probably less stable than win98.
I never reformatted and reinstalled from when I upgraded from win95 to win98 and then to win98SE and then to win XP Pro, they were all Upgrades in situ and that is probably the worst case scenario an upgrade over an existing OS installation often left remnants. But it was possible to keep your system trim ensuring the junk was removed and resources under control.
Even when I upgraded my system, built my next system using many of the components from my old one, primarily the HDDs (or copy a mirror of my dick onto the new HD), Optical drives, RAM and graphics, so I managed to get away without a format and install for well over 6 years.