Nope C9 I never heard that one before. I'll try it.
I try to feel the twist grip moment of contact. So I watch one or the other butterfly lever and see if I can feel the moment of opening in the twist grip. Then I look at the other butterfly lever and see if I can find the same point of feelingb the opening.
You can also just check for the same amount of free play at the adjustment screws on the carbs. Well that may just be the initial setting.