Are you asking about buying 2 OTM options and selling 1 closer? If that is true, you would do that looking for a binary event in one direction. If the event does not occur, or if the stock stands still or moves in the other direction, you will lose little or if you set up for a credit, make money. If you just bought a call or put, you would be a loser if you don't pick the right direction.
I'm not a big fan of the buy 2, sell 1 unless the market is really mispriced, which can happen more often on the call side.