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...the most important thing I've noticed is that it has to be 4-5 people/bubble time.

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That's the most importan caveat for me, also. I usually reserve it as a response to smaller bets and only after they've done the same thing a few times. I like to bluff the flop instead of raise them off their hand pre-flop because a lot of players will call a 3-4xbb raise to see three cards.