I don't use the same username all the time, but I tend to at least use variants of the same username. (Versions of "azuremist", "azure", and "bede" for personal accounts, and variants of "artsy azure" for my art accounts.) I prefer to have all of my internet presences connected. However, there have been a few times where I've undergone a whole new identity entirely. (Mostly in spaces related to illegal activities. Yar har fiddle dee dee, etc)
That sort of thing definitely isn't for everyone, though. It's easier for bad actors to follow you from platform to platform during harassment campaigns this way (speaking from experience). It's def a matter of personal preference.