Long is most common in questions and negative sentences, and after too and so.
- How long did you wait? I didn’t play for long.
The concert was too long.
In affirmative sentences, we usually use a long time.
- I waited (for) a long time (I waited long is possible, but not usual.) It takes a long time to get to her house.
Much, many and far are also more common in questions and negative sentences.