i have never adjusted my needle for winter riding, only the airscrew and bump the main up one size,
i do this once temps get into the low 50's and have never had a problem
any lower than 30's and it may need more ??? i'm not sure as you won't catch me riding in much below freezing.
and usually i only ride in those temps for hunting purposes, which usually doesn't include much "ripping" just putting around