I am talking specifically in rapid games, are notes allowed for say openings, since you can't just branch out and memorize everything right away and have to memorize while playing?
No. You cannot use any reference materials when playing Live chess games (bullet, blitz, rapid).
https://www.chess.com/legal/fair-play
- You may use Opening Explorer or other books without engine evaluations in Daily chess only (not in Online / Live play)
I am talking specifically in rapid games, are notes allowed for say openings, since you can't just branch out and memorize everything right away and have to memorize while playing?