For me personally, I think the wider 40mm and 50mm straps are most comfortable to wear any bag style or size crossbody style. That being said, however, for bags like a bolide 31 (or smaller) or Kelly 32 (or smaller), the narrower 25mm strap isn’t necessarily uncomfortable for crossbody wear. I use my multicolor 25mm wide 105cm long sangle cavale on my tri-berry Kelly 32 retourne all the time because the canvas strap colors work so well with my Kelly’s three colors raisin, tosca, and rubis. For crossbody wear, my SA thinks the narrower 25mm straps look “better” on Kellys because Kellys have a “more feminine” and complicated style with the delicate strap closures whereas the wider straps look “better” on bolides and evelynes because they have a simple style and structure. Lol. I don’t necessarily agree or disagree. I just know that my bolide 37/35 and Kelly 35 definitely feels better with the wider straps but for all of the other sizes, I feel fine using either the wide or narrow straps. Because the original straps that come with the bolide and Kelly are narrow, I like to use wide straps on everything. For example, I realize that a wide strap probably isn’t necessary (comfort-wise) for a Kelly 20 or 25, but I like the contrast in look between the teeny bag and the wide strap. Does this help at all?