If they think they can utilize a particular card in a future turn, they might need to hold onto it for a long time. On the other hand, it could be wdragon vs tigerise to discard cards sooner rather than later if a player observes that an opponent is amassing particular suits or ranks in order to avoid giving them an advantage. In order to discard effectively, one must strike a balance between one's own strategy & consideration for the needs of opponents.
tod