I used to play Bluff as a kid, and we did not have the rule that only the next player can challenge. I agree that such a rule makes it better - and is necessary if you have more than 4 players. When we'd have, say, 6 players, almost every move would get challenged, and the winner usually was the one who never bluffs, which makes it a lot less fun.
>and the winner usually was the one who never bluffs
Once everyone starts playing by this strategy people will not want to challenge as they will always fail. Since people are no longer challenging it is safer to start cheating again.
That's how I've always played too. If only the next player can challenge I can imagine table position would play a huge role in the outcome.
If you're able to pay in front of the most risk-averse player you probably won't be called on as many bluffs. If you play behind the most risk-averse player you probably won't have to risk challenging much either.
