When to use 132 fly rather than 121 fly?

Title

 

132 when you have a directional bias (trade puts for bullish & calls for bearish)
121 when you have a neutral bias (price likely to stay in a defined range)

***Not always but most often.

 

I think there is plenty of post by @destriero about it.

there is also one page where one guy collected all the related threads:
https://www.elitetrader.com/et/threads/the-staggered-butterflies.329827/page-3

 

Thanks for posting this.

Upon some more reflection I think that the 132/231 is about skew steepness more than anything else.

 

yep I think that the 132/231 fly is used instead of the 121 when there is a directional assumption and skew is steep.