user23037: (For reference) I'm a candidate master.
However, I've been trying to improve the tactical side of my game, especially calculations and time-management.
One thing I do a lot is double-checking my calculations. While it obviously contributes to my time trouble, this practice has saved me from quite a few blunders.
I've been reading a book by GM Smirnov, Champion Psychology. He strongly insists that it's a very bad habit, as it is a waste of time and proves my lack of self-confidence.
I'm shocked that in my many years of training I've never came across such a blunt opinion (except in Kotov's books, which are, however, strongly criticized e.g. by Nunn in Secrets of Practical Chess).
So what's the deal here? Do strong players (2400+) really not double-check their calculations even in classical time-control?

user9192: I think the key is to realize that what works for one person may not work for another person. Some people just make more careless mistakes than others 'by default' and have to make up for that by checking more. Just because one chess grandmaster tells you not to double-check does not at all mean that it is correct for you. In fact, not double-checking at all is definitely wrong for almost every chess player. What is definitely correct is that you have to figure out which subtrees of the search space you want to double-check. Maybe you are double-checking too many of them, and can do better if you skip checking some of the more clear-cut lines, or maybe not. Only you will be able to guess what is the best for you.
You also need to weigh the risks of making an error to guess how many times you want to check a subtree. I definitely check sacrifices a few times just to make sure I did not miss any possible case, because it is too painful to make erroneous sacrifices...

user8201: At shorter time controls, there is little time for conscious double-checking - perhaps there is a kind of parallel awareness of tactical risks and opportunities?
But at longer time controls: there is still a question of what economists call “opportunity cost” - what must I forego if I spend time instead double-checking certain lines?
I am not a serious chess player, but I do compose and solve chess problems, and in both these areas, I reckon that one weakness is I don’t consider enough candidates. I can plunge prematurely into examining detailed lines.
Sometimes that’s productive, but other times I miss better possibilities that I would discover through breadth-first strategic thinking. Effective strategic thinking is hard, but at least I’m aware of the issue and consciously try to work against it. It’s best to do the strategic thinking first, before I go deep and get emotionally invested in particular lines. Once I have an idea of the space of different strategies, then I can triage the most promising ones, then allocating appropriating time to each of them becomes easier, and brief double-checking is a later stage.
By the way, I think this applies to life in general, not just chess. There is no doubt a rack of self-help books about the importance of strategic thinking.

23037: <p>(For reference) I'm a candidate master.</p>
<p>However, I've been trying to improve the tactical side of my game, especially calculations and time-management.</p>
<p>One thing I do a lot is double-checking my calculations. While it obviously contributes to my time trouble, this practice has saved me from quite a few blunders.</p>
<p>I've been reading a book by GM Smirnov, Champion Psychology. He strongly insists that it's a very bad habit, as it is a waste of time and proves my lack of self-confidence.</p>
<p>I'm shocked that in my many years of training I've never came across such a blunt opinion (except in Kotov's books, which are, however, strongly criticized e.g. by Nunn in Secrets of Practical Chess).</p>
<p>So what's the deal here? Do strong players (2400+) really not double-check their calculations even in classical time-control?</p>
 9192: <p>I think the key is to realize that what works for one person may not work for another person. Some people just make more careless mistakes than others 'by default' and have to make up for that by checking more. Just because one chess grandmaster tells you not to double-check does not at all mean that it is correct for you. In fact, not double-checking at all is <em>definitely</em> wrong for almost every chess player. What is <em>definitely</em> correct is that you have to figure out which subtrees of the search space you want to double-check. Maybe you are double-checking too many of them, and can do better if you skip checking some of the more clear-cut lines, or maybe not. Only you will be able to guess what is the best for you.</p>
<p>You also need to weigh the risks of making an error to guess how many times you want to check a subtree. I definitely check sacrifices a few times just to make sure I did not miss any possible case, because it is too painful to make erroneous sacrifices...</p>
 8201: <p>At shorter time controls, there is little time for conscious double-checking - perhaps there is a kind of parallel awareness of tactical risks and opportunities?</p>
<p>But at longer time controls: there is still a question of what economists call “opportunity cost” - what must I forego if I spend time instead double-checking certain lines?</p>
<p>I am not a serious chess player, but I do compose and solve chess problems, and in both these areas, I reckon that one weakness is I don’t consider enough candidates. I can plunge prematurely into examining detailed lines.</p>
<p>Sometimes that’s productive, but other times I miss better possibilities that I would discover through breadth-first strategic thinking. Effective strategic thinking is hard, but at least I’m aware of the issue and consciously try to work against it. It’s best to do the strategic thinking first, before I go deep and get emotionally invested in particular lines. Once I have an idea of the space of different strategies, then I can triage the most promising ones, then allocating appropriating time to each of them becomes easier, and brief double-checking is a later stage.</p>
<p>By the way, I think this applies to life in general, not just chess. There is no doubt a rack of self-help books about the importance of strategic thinking.</p>
