To start with, I agree with the statement that sometimes you can't really manage. You can manage yourself over time. Time is free and it flows steadily, free like a river. How we perceive it and how we use it depends on us.
There are various techniques for effectively scheduling your activities over time. However, I would like to write about a slightly different perspective on "time management". In my opinion, introducing changes in the field that I want to write about may bring incomparably greater benefits than mastery in any of the typical techniques.
This absolutely does not mean that I disagree with these techniques. On the contrary - I use them in my own life. However, I would like to show a broader context of our "being", tell about a general compass, without which we can manage time extremely effectively, but sometimes badly invested.
So let's start with a brief description of common techniques.