Depending on engine size, prop size/weight, weather and geographic details, and the brand of engine, how far rich of peak you should set your high speed needle can vary significantly.

I was trying to tune a Magnum XLS .46A last spring for some club racing, and I had dialed it in like my Enya, Super Tigre, and Thunder Tiger 2-strokes. It would run really strong initially and then sag and bog down after a few minutes of flying. I discovered that I had to richen the high speed needle almost a full half turn rich of peak. The Magnum unloaded more in the air than my other two-strokes, and what sounded like a great tune on the ground ended up too lean while flying full throttle up in the air.

There is no such thing as a "factory" or "recommended" needle setting. Glow engines have a wide range of carburetor adjustment specifically because there are so many variables; altitude, humidity, temperature, prop size, prop weight, prop load, prop balance, spinner weight, spinner balance, glow plug heat, glow plug length, fuel quality, fuel lubrication content percentage, fuel lubrication content type, fuel nitromethane percentage, fuel tank placement, fuel tank distance from carburetor, quality of o-rings, quality of gaskets, and presence/condition/quality of on-board fuel filters all affect engine tuning.

If backing out 2 clicks is working for you, that's great. When it turns out to not be great anymore, however, don't be afraid to take the time to experiment a little bit and see how the engine responds to minor adjustments. "Rich enough" when it's 65F degrees and 50% humidity usually isn't "rich enough" when it's 93F degrees and 85% humidity.