Well, I cheated a little, because it was a kid, not an adult. So yeah, he had time
I think he was 1800 at the end of the year. I think he's an IM now? I can't remember his name. I'd have to ask some people I know.
And unless I'm mixing him up with someone else, he said that every Thursday or Friday he'd start to get excited... because that meant it was close to Saturday, and every Saturday he spent at the chess club playing in a tournament.
To rephrase how far do you think someone of my age could go with consistent study and work
If you're the greatest chess genius who has ever started at age 18, who knows. Probably you could be a pretty strong GM.
I'm not a sports psychologist (or any kind of psychologist lol) but the fact that you're asking this question gives me the feeling you don't have the ideal mindset.
As I said in my first post, the "secret" is you enjoy doing the right kinds of work. And if that were true for you, I don't think you'd be on a forum asking what your max potential is with a 1000 rating and 100 games played.
I knew a guy who bought about 40 chess books and read them all in 1 year. Well, that's not accurate. He read them all in 6 months, then in the next 6 months he read them all again. He went to an OTB tournament every weekend.
Are you going to remember 40 books in 6 months? Hell no. He didn't either. But he just loved to play and loved to learn. That's the sort of obsession/passion you'd need to be the absolute 100% best you can be... and no offense to people who do this, but that's not what a sane, normal, healthy person does. A normal person gives an hour or two a day or chess, at most, because they also have a family, job, other relationships, other interests, etc.
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So if you have a passion, great! I assume everyone on this forum has felt the passion for chess to one degree or another. We can relate. But if you have the sort of extreme passion necessary to be, lets say an IM or GM, you'll be out there living chess to the fullest (heh ) and not in the forum worrying about how good you'll get.
Wow. What a story. Do you know his rating at the beginning of journey and his rating at the end of one year or so? Approximate rating is fine.
And obviously he had enough time to pursue this regimen.