I've never used a set number of clicks or a set number of rpm to set the needle by. I set the needle by pinching the fuel line and to get a noticeable change in rpm. Ive found some engines are too lean at the typical settings, but setting by the pinch method puts it in its happy place - which ends up being 500-800rpm rich from peak. On 4-strones, I use a tach only to set the needle. Start over-rich with misfiring, lean it until it just cleans out and runs smooth. Ends up being about the same rpm rich from peak as with 2-strokes.

This still doesn't answer the question if nitromethane oxide is formed by over-leaning the needle valve.