I think it depends on the wrist of the wearer, and also of the watch...
A dressy and elegant watch may be a bit smaller, like 35 / 37mm, and looses its elegance if 42 mm.
We also may note that some watches that were originally 35 / 37 mm have problems when getting bigger.
A sporty watch may be more exuberant, without problems, and reach 42/ 44 mm.
A toolwatch can also be bigger.
It depends on a lot of factors, I think, but the most important one is to not look ridiculous when you have a very small wrsit and that you put a 60mm watch, LOL
Thanks a lot ofr your work, it was informative, and very niteresting!
Nicolas.