We used to pick a specific card for 2 - 4 players.
For me it was K
I got paid on a flop with
1 SB for 2 of my suit or rank (2 non-king clubs, 2 non-club Kings)
2 SB for all 3 my suit or rank (3 non-king clubs, 3 non-club Kings)
Bonus SB if my exact card flops, making a 3 SB payout the most per flop, and even allowing a 1 SB for just my exact card (and not an additional club or King to go with it).
Slowing the game down is the worst. Not everyone can handle multiple thoughts at the same time, and players not involved really hated the slowdown from some players.
We paid out on the flop, and I'd like to think that I never slowed the game down, playing in turn, then taking care of the prop bets. I know that other players in the hand would settle up props, then move on to playing their hand and that was wrong.
Still others saw chips being tossed to other players, weren't really paying attention themselves and thought there was action on the hand.
It's now rare that we play that game