bingohandjob is spot on with the clean cycle and usage. We run once or twice a day and have been fine in our hard water area.
Get a delayed start feature though so you can pack and run o/night to unpack the next day. That way you can set after dinner and put extras in before bed but if you forget the extras it will run anyway. I don't think we use anything other than "eco" which works fine.
A cutlery tray above all the others is a good idea, we have one in the washer in the place we rent out on airbnb at the moment, but people get confused and don't remember it's there!