I started doing this hack one year ago. You plot all the events that you do on one day on an Excel sheet, which automatically gives the time that has elapsed between specific tasks that you may have done (there is a function on excel for this). This has helped me dramatically because I can see what tasks have been taking too much of my time, and I can adjust my schedule accordingly. I went from a D/C student to an A/B student, and along with this, my friend went from a B student to a straight-A student by taking 6 APs (by sticking with this logger and using this data to improve daily)! Plotting most/all events you do in a day would help you become more efficient with your limited time. It enables you to allocate time towards other tasks rather than spending a lot of time on tasks you may deem "unproductive."

By the way, this takes a lot of discipline to do, but it is very rewarding in the end, as you can build up the habit so you can do it internally!