Doing the tactical exercises is very draining, both on time and energy. But we should not forget that doing exercises, and playing games are two separate things. In a 30-move game, not all those moves are going to be about tactics. There are a lot more involved in playing a complete game. Things like time management, psychology, prophylaxis, etc. My recent tournament results proved to me that studying is not enough. I can't just study for three months, then suddenly play like Kasparov. This is akin to a chain-smoker quitting cold turkey. Regular play must be mixed with study to bring it all together.
And so I decided to play at least four games a week.
Though I know that this will delay the circles the results have been very encouraging. Playing regularly strengthens my ability to judge positions and allows me to apply all those tactical ideas I've memorized.
Why the circles work
I think one of the reasons the circles work, is that due to the repetitions, there will come some point in time, maybe in the second, maybe in the seventh circle, you suddenly understand a problem. The cartoon lighbulb suddenly appears in your head. It happened quite a few times to me. And only now when I am now in the fourth circle. I would stare at a problem, then instead of variations coming to me, what I would see is the idea. After that, everything falls into place, and solving the problem becomes almost trivial. Tempo posted about seing all the moves in one tempo - this is maybe what he is talking about. I'm sure all the knights will experience something similar like this.
I am falling behind the circles as I keep on reviewing the problems I have missed, and my study time is now down to 1 hour, but even if slowly, well get there.
Problem Start of Chapter 10: Demolition of Pawn Strukture