It doesn't back test well for either. Here's the 7 day. http://tm.cmlviz.com/index.php?share_key=20180206233312_BzKlJNzU8CTBEZj9
3 day http://tm.cmlviz.com/index.php?share_key=20180206233502_Iy3jN3ldDX0UPXnT
@samicoThere is a difference between a spike where a subsequent pullback is likely compared to a extended period of high volatility where you establish a new average VIX level. The biggest problem for straddles is falling IV.