Magicians and mentalists get this question all the time. Though most of my work now involves guessing what people are thinking, I started my career as a close up magician focussing on card magic. At 6 or 7, I always had a deck of cards in hand, and I started practicing 4-6 hours a day in middle school. I studied both sleight of hand card magic and card flourishing, which involve fancy cuts and fans and was recently dubbed “cardistry” (a portmanteau of “card” and “artistry”). As you handle the cards, the cards pick up the natural oils from your hands. When you drop them, as is inevitable when you’re practicing, the cards pick up little dings and dirt. Ultimately through these processes, cards lose their uniformity and look and handle differently from each other. This makes them respond in unpredictable ways, and they’re therefore unusable for a professional card handler (aside from looking unsightly). All this to say, I slowly progressed from a pack a week habit to a pack a day.
At 14, my fledgling magic career funded bulk card deck purchases (known as “bricks”–12 decks/box) at Costco (still the cheapest source when buying less than 5,000 decks at a time). Sometime in the 2010s, the cards supplied to Costco became lower and lower quality. I felt I could no longer rely on them for more advanced sleight of hand and started purchasing decks made exclusively for working magicians. These decks, though not altered in any way to achieve a magic trick, were simply made to a higher quality.
The quality of cards, in my opinion, is measured by both the finish and the cut of the cards. The blades that cut the cards dull after cutting thousands of cards a day, which mean the cards cut at the end of the day often have slightly rough edges. To a normal poker player, the difference is negligible and unimportant. However, when you start performing complicated sleight of hand, the smoothness of the edges of the cards becomes quite important. So the decks I buy, and the decks manufactured for magicians (again, most of these are ungimmicked), are cut with recently sharpened blades, ensuring an evenly cut edge. They are also occasionally pressed, which makes the cards feel softer and more “broken in.”
These days I don’t practice nearly as much card magic as I did in middle school and high school, but I still touch a deck of cards at least once a day aside from performing. I also always like to perform with a fresh deck as it feels nicer and looks sharper.
To answer the original question, I go through around 100 decks a year.
