“one of the other party would’ve borne the Ring for the remainder of the trip to Rivendell”
You keep saying this, but it neglects to take into account what we already know from the story. Nobody else but Boromir (and Bilbo) had any inclination to even touch the ring, because they were either too afraid of the burden it would entail, or they were aware that it would destroy them. Perhaps the Black Riders, informed by Sauron’s Eye, knew that as well. Perhaps they wanted Boromir to be the only choice to bear the ring, knowing he would succumb to it easily, but that he would never realize that was coming because of his pride.
Or perhaps Gandalf would have vetoed Boromir and reluctantly let Bilbo bear the ring again, but that would have ended just as disastrously.
It’s a bit of a silly argument, I think, because the elves saving Frodo was a bit of deus ex machina, and you can never expect the villains in a story to account for a deus ex machina when they hatch their plans :)
Of course, Sam took the Ring when he thought Frodo had been killed by Shelob. You do what you gotta do.
What you say about the big picture, I don’t disagree.
But just in the context of the trip from Bree to Rivendell, I don’t think the Black Riders tactics made sense.