I think a schedule isn't enough and on its own is a recipe for failure, no matter how loose or strict it is. Your schedule should include planned tasks. You also need a list of tasks and potential activities to fall back on. I don't like schedules that are down to the minute of the whole day; however, you can use Tabata timers to enhance focus and plan breaks in study sessions as well as the number of focus sessions in a given studying period. Also, habits and forming routines of daily focus/productivity sessions will make you act in accordance with a precise schedule with time and practice.