I start looking at +3 in my man D when I see a team shoots over 40% in 3 pters. If they actually have sharp shooters it's a definite. I can't say I've gone +4 before but I'm willing to give it  shot if it's the difference in a W or L. I think too many coaches don't take the risk and always stay within + or -2.

I have recently gone +4 before, against a team that shot took over 1k 3pta on 1800 overall shots. I actually lost the game but I believe it was the right move. 

Edit: I have gone +5 a couple of times a few months back in D3, and they resulted in wins.

My thinking is, if you are facing a team that takes no threes, you would probably run -4 or -5. What's the equivalent of this situation? It's probably something around 50-60% 3s, because taking all 3s is impossible, so this deserves a +4 or +5.