OP advice doesnt work with everyone. For example, Im rated 2200 in tactics but only 1250-1300 in blitz/rapid.
Something is really missing in my game knowledge, and it is not tactics.
Correct! It's not tactics. You lose because of blunders. Playing a whole game without making a blunder is one of the hardest things in chess. Take a look at the games you have lost to check out how many of them you have lost because you make a move so that your opponent can simply take a piece because that piece is unprotected. You will be surprised of how often that is the reason why you lose. If you don't lose because of that, it's probably because of another simple blunder. You don't lose because of some 2200 rated combo firework.
Watermelon
thank you for your meaningful and insightful comment.
I applaud you for this groundbreaking idea.