For someone who was never a hooker with my irons, but likes to try NHA from time to time, I personally feel that it is easy to overdo the carry. If you weren't severely underplane before, feeling like you need a bunch of carry may likely result in what would be severe enough to be called OTT.
I think it's important to realize that if you already take the club up outside the line, it shouldn't take much more than feeling like you're "dropping it back down that same line" to get the slighly outside in path. It is definitely a feel v. real thing, but if you "over carry" from an already outside the line backswing, you will have a lot of dropping to do at the last minute to get to the ball at all, which will probably result in some weird shots.
For me, a former laid off OTT'er, I don't have to feel that much carry at all to hit a baby fade, from the NHA backswing. It's really easy for me to overdo it. Just my .02