When an opponent routinely selects particular ranks or suits from the discard pile, for instance, it can be a sign that they are attempting to make a partionline rummy gamecular meld. In these situations, it might be prudent to keep cards that could help them finish their hands from being discarded. On the other hand, you might have a chance to play more aggressively if your opponent shows signs of having trouble with their hand, such as discarding high-value cards frequently.
