Question: How many Jokers can a player use in an exposure?

Answer: A player may use as many jokers as needed to call (claim) a tile needed to complete a Pung, Kong, Quint, or Sextet. Other factors—such as whether you’re in the beginning, middle, or end of the game—should influence your decision about when to use Jokers. For example, using all of your Jokers early in the game to make a call might leave you unable to call other needed tiles later. However, if you’re in the end game and already set for Mah Jongg, using your Jokers at that point may be a smart and strategic move.

Source:  Mah Jongg Made Easy 2024 page 24, #12, and page 31, para. 5