You're going to "waste" time, whether you plan for it or not. If you don't plan your wasted time, it really will be wasted by procrastinating. You will end up doing something you don't really want to do (hi Reddit), and feel guilty the whole time about not doing work. Instead, put leisure time on the calendar and use it for just that, and put focused work time on the calendar and don't deviate from it. Your time will be better spent, and you'll not have to feel guilty about enjoying the other stuff. The other stuff is important to you as a whole person.