This could be the case. Although, it's slightly depressing if it is.

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be immersed

Why is it important to you to only play at your highest, best performance every time you play? I feel that this is an unrealistic expectation and you're putting yourself under immense and undue pressure. This pressure might hold you back more than anything else.

What's the underlying force? I wonder if it's fear. Fear of losing rank? I don't get that vibe from your posts. Fear of stagnation? Fear of "feeling dumb"? Fear of "looking stupid"? It probably doesn't matter, though. If it is fear, it's probably worthwhile remembering that anxiety, phobias, etc. don't go away by themselves. They tend to first lead to avoidance and then slowly but surely limit you increasingly further. In this context, you might end up "feeling up to playing" less and less often, which then does impact your overall performance, giving another excuse to not play.

The solution? To play more, when you want to play (which doesn't necessarily mean you will "feel like it"). Desensitization might be the key, as it is for many anxiety-related issues. The trap is to think too much and do too little. Too much analyzing, too little practice. Gowan's book recommendation may be worth considering, too, though it will only provide ideas. You still have to "do" it. If it is fear, don't let it cripple you, your enjoyment of the game, and your freedom to play when you want to play.

I may be well off here, but I wanted to chip in a few thoughts.

Try some blitz games in between. (You can take a different account for that.)

The pressure to play your best game may actually be harmful, if too strong. If you want to improve (and you = Kirby want that very much as far as I know although you doubt it will happen) you need to be relaxed enough to change your game and your playing habits. But of course it is easier said than done with the nagging feeling of stagnation in your neck, while it is easy to have confidence to let go and try new things when you feel you are improving. Vicious circle.

I doubt that any external method to gain balance is very useful. The only workable way to find balance as a Go player is to find it in your game and use playing as a way to focus and calm down.