?? first off I didn't see the post so apologize.  Secondly that is not really a system, it's more of a guide.  Now most of the time when the VIX is behaving normally closes back inside the VIX work pretty well.  One of you guys should take the VIX and SPX chart and try to do some history back 15 years and compile the data in a spreadsheet and share. I think it tried doing that once but been a long time and I don't know where that it is.  Anyway in the times when the VIX moves VERY strongly up you will tend to get multiple bad signals where it closes back inside, then outside, then back inside and outside

see this quick chart - again under most VIX conditions that works well however on very sharp corrections when the VIX spikes way up you get many multiple whipsaw signals where you buy on the up day which causes the VIX to go back inside the bands and that's the one day bounce and crap.

now I think the VIX moving down like it has the last few days is far more interesting and yesterday probably good for a buy, but that wasn't one day inside the bands. 

Also note the VIX became uncorrelated to the SPX on that indicator below SPX

so normal times that one day close backinside is normally a good signal, sometimes it's good for 1 day, sometimes it's a major low or high. But when you get moves where the VIX spikes way up over 30 and 40 I think you can't simply use the 1 day close back inside the VIX as you can get multiple before it's correct. Switch to other charts for triggers