quote from TftC:
Let’s take another scenario. Many players ask whether keeping to the 50 card minimum is really that important. How does increasing the deck size affect the odds of drawing a key card? What if we increased our decks to a massive 60 cards to include all those cool effects we normally have to cut out? The probability would fall to 50%, which actually isn’t as precipitous a decline as I was expecting. Thus, the number of copies of a card is actually a bigger factor in the probability of drawing it than the deck size (assuming you’re not going crazy and inflating your deck to ungodly sizes). In fact, you’d have to go all the way up to around a 70 card deck before you would equal the impact of removing just one copy of the desired card. Of course, keep in mind that consistency means more than simply the probability of drawing a certain card in your hand, so don’t take this as an endorsement for building 60-card decks. 50 card decks are still the ideal if you want maximum consistency for your deck in general, not just in terms of one card (it would take further statistical modeling to prove this, which is beyond my attention span at the moment, but you’ll have to take my word for it). However, if you’re worried that using a 52-card deck (the size of a deck of cards for standard games like poker) will impact your chances of drawing a certain card dramatically, the actual impact is negligible (a 1% decrease).