No? It's a technique that could readily be done by one person, and teams are allowed to strategize. Bluffing/deception is kosher in chess, just harder as the key elements of the game are all public.

Before computers put an end to the practice, long games used to adjourn overnight. https://www.chess.com/terms/chess-adjournment

> During adjournments, players could count on the help of other strong masters, called seconds. These seconds would analyze the position and tell the player what they should play when the game resumed.