PhamENG:
Sounds like a very good point to me, particularly when in the one case you are talking about a distributed load and support system, with some adjacent redundancy, but in the other you are talking about a much larger concentrated load on only one member, with no redundancy. However, I suppose the laminating improves the general member strength and stiffness a little when done well and when the ends and member length are cut well to assure good unform bearing. I’ve seen built-up col. members cobbled together such that only about half of the verts. were end bearing until something crushed 1/8th or 3/16ths of an inch or so. It seems that builders think that the number of plies is the only important issue, not how the load gets to all of them, and the rest of the details can be cobbled. Look at how the NDS, some good texts, and various research treat individual studs, and repetitive stud groups, and/or built-up members both solid and intermittently blocked, how they develop their approach, and rationalize it, explain it. That should give you some insight. Otherwise, I agree with your thinking that sht. rk. bracing a single 2x is quite different than the same sht. rk. bracing a huskier col. member with a large concentrated loading. Even dry sht. rk. nailing just won’t take some percentage (what % that is?) of that larger vert. load as a bracing load component.
