by Thanee
Cards that are non-unique and you are basically always happy to have in your hand (like Sneak Attack or A Test of Will) end up in the deck as often as possible (3 copies, or as many as you have in case of some Core Set cards).Cards that are unique and which you want to draw early (like Steward of Gondor or Light of Valinor or Asfaloth) end up in the deck as often as possible (3 copies, or as many as you have in case of some Core Set cards).
This is especially true for "combo cards", which you need to pull off some tactics you build into your deck (like Sneak Attack and Gandalf), since you need to have them both together (of course, it is better if the cards are useful on their own, too, or in combination with other cards, to improve their overall usefulness), because you need to get them together, which makes it even less likely if you did not include the maximum number into your deck.
Cards that "thin" the deck and thus make it more likely to get to the important cards (like Daeron's Runes) are also a good choice for 3 copies.
Other cards are added in less often, usually based upon how useful it is to get the card more than once, and how useful the card is in general. I usually put only one copy of unique allies into the deck, unless they have a specific function, which makes it important to get them into your hand (i.e. my current non-solo Ld/Sp deck has 3x Arwen and 3x Gandalf in it, because of their overall usefulness).
Of course, sometimes (read: always) you will end up putting waaaay too many cards into the deck, if you add everything that is useful, therefore you need to make a cut based on deck composition (i.e. number of allies/attachments/events as well as card cost/sphere distribution) and other factors (which cards are really necessary, which are just "nice to have").
It is good to have a way to make use of cards that you cannot play (anymore), i.e. the second copy of the same unique card (unless it is useful to keep it in reserve in case the first goes to the discard pile for some reason). Eowyn is an obvious example, or the Protector of Lorien.
Bye
Thanee