Then you can appreciate that people with narrow sit bones and the narrower ‘gap in the middle’ that sometimes comes with them get friction from the edges of wider saddles at the top of the thights, especially if they ride a road bike with a narrower Q-factor. People come in different shapes and sizes, that is why some saddles are narrower than others.
Never had my sit bones measured but I did have a brooks B17 saddle given to me after a friend had broken it in over a few 1000miles, his sit bones were clearly marked in the leather and after some use mine were visible 2cm narrower and further back, I swapped it for a brooks swift that was narrower and more comfortable.
As for padded shorts? No idea if they are size specific, they certainly are more flexible and conform to the body more than a saddle. 🙄
Specialized toupe, San Marco Regale and the narrower pro-logos work for me.