When it first came out my family had it, I was 17 I think. As I remember, then I might have known 1 of every 4 answers or so.
Thought of it for some reason and it just came today. My brother is coming over tomorrow for dinner (honey garlic chicken) and mass quantities.
I am wondering how many games it will take before it becomes boring.
We’ll probaly play once a week. Some assumptions

A game takes an hour (on Amazon it said the average game was 1.5 hours), 30 seconds per question. That is 120 questions. There are 2400, so after 20 games we will have seen all questions, if number 3 is correct (which it isn’t but it makes the math easier).

We do not shuffle the cards after each game, we go in order

The questions come up equally distributred, none are duplicated. Obviously not going to happen, after 20 games each card will come up 6 times. There are 6 categories.

Once you have seen a question you don’t already know, you remember the answer for all subsequent games.
After 20 games, we will know all the answers, assuming the above. So after 19 games we will know 95%, after 18 we will know 90%, down to 75% after 15 games.
So after about 1012 games, it comes down mostly to luck.
But, how does the random distribution of the questions that come up figure in? You may get 1 question that comes up 34 times, some that only come up 1 time. I’m thinking that the number will be very small, yeah there may be 10 or 20 questions you never get. Even if there were 100, that is less that 5% .
I was going to play a joke and cheat for the first turn and memorize the first 10 cards. But going through them, I knew about half the answers. Didn’t want to spoil what might have been a very good run on my first turn.
As an aside, how would you calculate how many questions of the 2400 would come up in a 20 game sequence?