As you turn the screw in, it exentually contacts the throttle slide. Twisting the throttle simply lifts the slide out of the screw's way instead of moving it with the screw. Then, when you turn the screw in and lower the slide again, it will be resting on the screw tip.
It probably makes little difference, but I like the idea of parts being moved the easy way.
The main jet makes close to zero difference to the idle mixture.
The fact that you mention a new jet, leads me to ask if the answers to my 2 questions in my first post, were really "yes".
If they were not, please say so or I am pissing in the wind here.
Btw, when did your ped quit idling?