Cruft is left around from caches and old program data all the time. A clean install handles that, and lets me verify my configs are still good and think about w

Cruft is left around from caches and old program data all the time. A clean install handles that, and lets me verify my configs are still good and think about way to change them. Clean installs also let me do full-drive SSD trims. I do OS reinstalls maybe 1-2 times a month unless I'm testing something, and can re-deploy my personalized set-up in less than an hour. I'd rather nuke from orbit and rebuild than duct-tape holes :p If my system became unbootable for some reason, I'd fix it and ideally find out what happened, backup stuff, and reinstall. Best-case, everything is fine (although I'd change distros if it ever broke because of a clearly untested updated). Worst-case, the system becomes unbootable again because of the same issue and I can report it upstream with more confidence.