Lesson about decking that Magic taught me (applied to LotR):
Discarding from the top of the deck is only a good strategy if
(a) you get rid of the whole deck (preventing them from drawing cards)
or
they've manipulated the top card to help them
Otherwise, you're just changing their random draw for another random draw. You are just as likely to cause them to draw the card they need (by getting rid of junk on top of it) as you are to discard the card they need and make them draw junk.