Os 32
The idle needle has most effect when the carburetor's opened to about 1/3 or lower.
Both adjustments are working to one degree or another. The high-speed needle is the master control for the carburetor. The idle mixture has most effect below 1/2 throttle, but affects fuel flow at all settings, depending upon how you have the idle mixture set. The design of the carburetor is such that both working in concert help to adjust the fuel flow at various throttle settings.