Phones are an addiction. I know executives who have a box outside the conference room and everyone has to put their phone in the box as they enter the meeting. They pick up their phone on the way out.
After seeing this happen for years, it comes down to one simple thing, at least while at the office. Is the employee getting paid enough? If they are, they will use the phone less. The more junior the employee, the worse they're getting paid, and so the more they will use their phone.
I am not going to allow anyone else to touch my phone, even by mistake. In fact it is zipped to my clothing, so I don't lose it by accident either. If I were to leave it in a box, if will definitely get lost one day.