Number of people in a room doesn't affect the payout structure but it can make a HUGE different in one's odds of winning. The bingo hall has to pay its standard winnings whether 30 people or 300 people are in a room. Odds go up dramatically of course when there are fewer people. It's why I sometimes play 11 pm sessions during the week when I am in Vegas. Prizes may not be as big but I literally have played when around a couple of dozen people were playing. It doesn't guarantee a win of course but you're competing against a much smaller number of bingo cards.
