Planning the opposite

I was puzzled by the questions of personal efficiency, where much attention is paid to planning. For me to plan my next day is not an easy task, and to fulfill this plan ... And now the thought came to me that planning is essentially a pre-moderation of my time, and there is, as we know, also post-moderation. The point is that it may be quite effective not to plan the next day, but to analyze the previous one. Knowing how much time I spent on work, and how much I was idle about, you can at least just assess the extent of your own crucifixes ***** and after taking some measures. The very awareness of this degree can give a serious impetus to further self-development.

You can implement 2 ways. Or open a diary at the end of the day and record everything in hindsight, or carry a stopwatch with you (PDA, cell phone).

I think as a first step towards improving our own efficiency, this method can be effective. What do you think? Maybe something like this has already been invented / described (not googled in particular, for 6 am)?