This is more about how to save time tip, not really how to self-improve in five minutes. Although, you can try that one too. You actually need only five minutes daily of planning to repurpose all your wasted minutes - and that would be much better than doing absolutely nothing about it.
Philosophically, and biologically looking at this time wasting problem - we do not waste time, in general, we waste our life. Now, if you waste your life into something meaningful, useful, to you and others - your life is not wasted. But if you just go about your day without any planning, you personally will not be satisfied how you spent your days in this place.
We think that life is long, but at the end, everyone wants just one thing - to have more time to do all the things one missed during their lifetime.
So, how will we cut down all the meaningless rattle out of our time table. Well, easy. Cut all garbage out. It simple as that. Just trash all you don't need. You can also clean your personal space where you are at that task. It will help you concentrate better.
Second, cut all your tasks on minimum achievable for that day and give an each a time frame. Every day you will do these tasks, until you need far less time to complete all of them. So, instead wasting half day on some, or more, you will be done much faster.