I would require a shorter strap as I was already on the last hole and still needed a bit smaller on the 40mm with strap.
Again, I don't think it has anything to do with the diameter of the watch itself, more about the straight lugs and how they extend. If they were slightly curved, they would hug the wrist better, especially for smaller wrists.
I wear much larger watches which fit better than this 40mm La Tradition due to the shape and length of the lugs.
My JLC Extreme Lab 2 is 46.8mm and wears better than this 40mm La Tradition due to the articulating lug system. Same thing applies to my Blancpain FFs which are 45mm. Lug shape, length, and curvature have more to due with fit than the actual diameter of the watch when it comes to smaller wrists 😁