[robomartin]

The point is that the extremes are bad. If someone spent ten hours a day doing nothing but building legos the observation would be exactly the same: It's not good for you.

Chess can become a sick obsession. I know. I've been there. I have played chess for 12 hours straight on more than one occasion. It leaves you rattled and with nothing good to show for it. Contrast that to spending twelve hours with a mixed bag of skills: learning to play the guitar, watching a tutorial or two, taking in a couple TED talks, etc.

My greater point might be that if you have x amount of hours per day to devote to something it is probably a bad idea to devote too much of it to Chess. You are going to get nowhere by playing chess the way you learned it. The only way to start climbing up the ranks is to become a human database. That takes you in a very different direction.

[D_Alex]

"extremes are bad"

I disagree, a little. Extremes are good, because a bunch of worthwhile things get accomplished by people going to extremes.

As far as personal costs of going to such extremes go - they are difficult to judge objectively, from the outside. A study I recall claimed that elite athletes are "happiest", based on self-assessment, and it further speculates that one reason for this is because they have a clear goal and a clear way to advance it.

[jinfiesto]

All the same, I don't think playing that much really does much for your chess skills either. There's really only so much information you can absorb in a day. As an analogue, Richter, one of the greatest pianists of all time, regularly only practiced 3 hours a day.