Yes, the geographical location may very well make a difference. I remember Adams writing about this. According to him, before exposure meters were available, photographers carried around exposure charts of some sort. But they were derived from measurements (or experiments) at a specific location. Adams said he learned this when he tried his California charts on the East coast somewhere and found they were all hosed up.
Originally Posted by juan
Weston was fully engaged in photography well before exposure meters came along. That may explain why his legend says he never used on. I've learned that from my experience in the local area that the exposures are pretty much the same based on the cloud/sun conditions. I could probably get along fine without a meter anywhere in the region.