>>41942695Billions is a stretch, as while Yu-Gi-Oh is very popular in the world, you're still talking about a single company printing all of those cards. Just for comparison, MTG has been around for 25 years. If you assume they made 10x as many unique cards as they already do, and you multiplied that by 4 to have them active for 100 years, that'd be 400,000 cards. That's still a metric fuckload of course, but that's a far cry from a billion.
However, I don't think there would even be that many. Usually whenever we see non-main characters dueling, a lot of them are using actual existing cards. When Chazz goes to North Academy, the cards he gathers seem to mostly be pretty common existing cards. When Yusei has to build a deck in prison, all the cards we see him get also seem to be fairly standard cards like Axe of Despair or The Unhappy Maiden.
When you also factor in the fact that most of the time, you'd simply be trying to learn the ace monsters and general key cards of various archetypes, it'd be far simpler. You don't need to know exactly what all the Armed Dragon monsters do, but knowing how level monsters work and knowing Armed Dragon destroys your monsters is enough to not do what Jaden did and use a trap to try and prevent it from attacking his monster.
And of course, the other benefit is that a lot of Yu-Gi-Oh duels take place in the context of tournaments where you would certainly have time to watch replays of the duels of other competitors to learn at least something about their cards. Simply being able to think about reading a card before its effect matters would be a major advantage.
