A complete reinstall of a modern Ubuntu on a spinning HDD takes less than 30 minutes in my experience (often less than 15).
Windows installs and reinstalls take hours more often than not -- just logging in for the first time on an up-to-date Win10 laptop recently took 10 minutes to "personalize" it for me ... and this was on an SSD. I used to have curiosity about how they made it so bad, but these days I've placed anything windows under a SEP field.
My last windows install was about 30 minutes from boot to actually on desktop (very frustratingly interactive though, blocking the last 10 minutes behind that personalizing dialog)
Windows installs and reinstalls take hours more often than not -- just logging in for the first time on an up-to-date Win10 laptop recently took 10 minutes to "personalize" it for me ... and this was on an SSD. I used to have curiosity about how they made it so bad, but these days I've placed anything windows under a SEP field.