You could easily leave it on during the night (up to level 3). Levels 1 and 2 are hardly noticeable. You can hear level 3, but I don't find it disturbing. I leave it on level 3 with a timer of 2 hours.
It depends on what water hardness you have. I have hard water and the app says you have to do a deep clean after 650 hours. You can also control the water hardness in the app.