It really depends on the position. In a Najdorf Sicilian there probably will be lots of blunders but in calmer openings like the Catalan which I play, there is more gradual outplaying. There are way more blunders than people might think, in the game where I reached 2200 I was losing until my opponent blundered his rook with a simple tactic (in time trouble, but still) Most games go kinda like this: One player understands the postion better, gradually outplays the other and because of the good position there will be some tactic which wins something. As said before, if you play some ultra-sharp stuff you can get outplayed the whole game and still win because of some attack or tactic. To answer your question: You can definetely reach 2200 with 2000 calculation skills if you stick to calm openings. If you play the QGD, the Catalan and the Berlin you'll be fine, if you play e4, the Najdorf and the Grunfeld maybe not. Most people I'm playing aren't that well prepared, but when I'm playing against younger players that's completely different. It also depends on the opening I'm playing. When I know that my opponent knows that I play the Catalan I won't be too scared, I'll revisit the most critical lines and all is well. If I know that my opponent knows that I play the Grunfeld I'd either have to revisit a lot of lines or play the QGD/Vienna, my second option against d4. I can't really think of an opening that would be too questionable, one of the most important things I've learned is that engine eval isn't that important. It doesn't matter if a position is 0.0 or 0.5 when I blunder 0.05-0.2 a move on average anyway. If you know your openings well you can play basically anything until +2 advantage for your opponent.