On lower levels coaches tell students their opponents don't know openings, so they don't have to either. Authors of opening materials targeted at club players often say that the lines they offer will get opponents out of book. Stronger players think about the strengths and weakness of their opponents, and do things like avoid complications against tactically superior players, or try to mix it up against tactically weaker ones. The ability of opponents always matters to your decision making. It's part of the practical side of the game. You just have to avoid letting it influence you too much so you aren't careless, or play too passively, etc.
On lower levels coaches tell students their opponents don't know openings, so they don't have to either. Authors of opening materials targeted at club players often say that the lines they offer will get opponents out of book. Stronger players think about the strengths and weakness of their opponents, and do things like avoid complications against tactically superior players, or try to mix it up against tactically weaker ones. The ability of opponents always matters to your decision making. It's part of the practical side of the game. You just have to avoid letting it influence you too much so you aren't careless, or play too passively, etc.
I agree, thanks for the comment.