One thing that I did when I was in school was seriously evaluate how it is that I learn most effectively. I noticed that the homework for subjects that used to be "easy" for me were taking up a ton of time so I started taking notes on what I was thinking and learning, and which lessons/activities were the easiest for me to remember and which ones I was struggling with. Essentially, performance debugging on my brain. What I found out was that there are some explanations, exercises, etc that come easy to me and others that are much more difficult for me to sort through and retain, and for some inexplicable reason, I wasn't dealing with them the same way that I dealt with the "easy" stuff. Once I had that sorted, I began paying more attention to what I was thinking during those subjects/exercises and "reigned myself in" any time I started to deviate from my "known good methodology." There was a marked increase in the speed at which I was completing homework which ended up equating to a lot of compounded time saved.

Long story short, schoolwork was a huge bottleneck and I figured out that I was treating certain subjects in less efficient manner than others, then made a conscious effort to handle said things better and reaped some time-saving rewards.

Another thing is to do like what @venam says and make lists, with time ranges, then set your watch/phone/time-tracking device to have many alarms. From there it's a matter of self-discipline to adhere strictly to the schedule you've laid out. Just make sure to remember that you are not a robot and can't switch contexts as fast as a computer, so throw in a few minutes between each task to "take a breather."