My question is about black 5 as C6. I recently played a game where I opened this way but instead chose to approach at R6. My theory was that this stone would work well with my star point stone. However, I had a 1 kyu review the game and he told me that this was wrong and that the proper move was at C6 and he said "that's why you played the 3x4 in the top left. You are not using your stones together very well!" Now I understand perfectly why C6 is also a fine move but don't get why it's so much better than R6 or even O3 and F3 for that matter.

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Thinking like a go player during a game of chess is like bringing a knife to a gun-fight. Thinking like a chess player during a game of go feels like getting knifed while you're holding a gun...

The Kobayashi style, in other words. It was invented by Kobayashi Koichi, for practical purposes; which means before he developed it, it hadn't been developed.

This is not meant as a tautology-fest: KK innovated, and the reasons he was successful with it are bound up with his attitude to frameworks. But also, we believe, with what he learned from Kajiwara about "sweating the stones".

These are relatively deep waters. At this stage of the game, there are typically half-a-dozen options for each play that are good enough for pros.

Don't believe everything you hear.

I know that you don't, anyway.

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The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

A couple of ideas come to mind which may be instructive. I'm to saying they are ideal as much as designed to make you think.

Suppose that with move 7 you extend to D10. What would white do. With the 3-4 in the top left an enclosure from you would be too good to allow and so white must approach. But if he plays low then a high two-point pincer will work well with the upper right and at the same time help to build up the left. If he plays high then you can attach on the outside and build a large moyo on the left.

Now move all that to the right, where you have a hoshi. It doesn't work the same. I am not saying that that makes C6 vaslty superior to R6, but it is certainly something to think over. But playing F3 or O3 is not so good. When white plays down the side he negates some of the influence of your fourth line stones at the top.

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Still officially AGA 5d but I play so irregularly these days that I am probably only 3d or 4d over the board (but hopefully still 5d in terms of knowledge, theory and the ability to contribute).

Haha, thanks and sorry I asked. My theory sounds more like "the star point stone wants to develop quickly where as the 3x4 is stronger and less urgent. Hopefully, he'll pincer my approach and I can develop my star point as I counter attack." Real Go players amaze me...

Btw, was black 111 necessary?

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Thinking like a go player during a game of chess is like bringing a knife to a gun-fight. Thinking like a chess player during a game of go feels like getting knifed while you're holding a gun...

o3 and f3 are quite easy to understand the difference: they are approaching from within white's sphere of influence (half of the board), breaking up that area, rather than extending from black's area; they are more of a destroying than building style. With the large komi these days black tends to prefer building something large himself, the breaking up the board into little pieces approach (e.g. amashi) is more suited to white with the komi.

r6 and c6 are both perfectly good moves and it really just depends on your game plan. I quite like making the c6 approach and then the Chinese opening if they answer with the low knight move (I find the Kobayashi boring and overused at low dan levels). Looking at pro game stats c6 was played 2431 times and won 52.6% versus r6 only 180 times but with a slightly higher (but probably not significantly) 55% win rate.

What no pro would play though is k3, can you see why?

Seeing as I wouldn't consider this move either, I'm unsure how to answer that. It does little to impede the development of the white star points.

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Thinking like a go player during a game of chess is like bringing a knife to a gun-fight. Thinking like a chess player during a game of go feels like getting knifed while you're holding a gun...

I meant white's k3 in the game.

Oh. Well, the invasion at H3 can weaken the corner, however, I chose not to play it because it seemed ill timed. More importantly, if I'm white then I really don't want black to play high chinese right now so the approach to the top left seems more urgent. What are you thinking about?

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Thinking like a go player during a game of chess is like bringing a knife to a gun-fight. Thinking like a chess player during a game of go feels like getting knifed while you're holding a gun...

Back to basics: Once groups in an area become settled, what usually happens to the value of further play in that area?

A pro game with 5 at r6:

https://www.youtube.com/watch?v=F7Jh5OnV6lo

The commentator does mention that it's unusual, but he doesn't say it's bad.