I know very often on Perry's version he would say "2 brand new decks of cards." I would hope, and at least assume that they perhaps had at least 1 "back up" deck for each color for the main game. Then there are the Money Cards, a separate deck of red cards (to me the Money Cards should have had their own color, like green for example). I imagine they had at least one "back up" up deck there too. Also, often there would be 2 matches played per day, or at least a part of 2 matches played per day, and presumably a new red deck for whoever the champion is would be available to be cut to start the next match, as well as another new blue deck for the next challenger who would be "waiting in the wings" to play. So I would imagine they had about 8 decks in use total, plus some "back up" decks in case a card was damaged somehow.
I'd LOVE to know whatever became of those cards after the show went off on both NBC & CBS. Did those respective art departments/Goodson-Todman KEEP those big cards for future use? Were they resurrected for when Ricki Lake did the Game Show Marathon?
I love questions like this. To answer the original question, I am postulating 8 decks, 5 red and 3 blue. Again, just my educated guess.