It’s such a nice habit to have!
This came up today because I notice that when we use a Keurig at other people’s houses, 95% of the time, there’s a used cartridge in the machine. It’s not a big deal, but it sure is nice to have the machine ready instead of having to get rid of the previous user’s leavings. And, as is the case with many other things like this, it only takes a minute to clean up afterwards, and it makes less work for the next person.