An efficient way to monitor your rivals' discards is to observe any patterns or trends in their discards. You can learn which cards your opponents might be collecting or avoidinanimal-themed slotsg by keeping an eye on the kinds of cards they are discarding most regularly. You can use this information to help you decide which cards from your own hand to keep and which to discard in a more informed manner. You can also anticipate which cards might be available for you to take up from the discard pile by monitoring the discards of your opponents.