My dance (Orlando) gets around 20-25 people, maybe 1/3 - 1/2 new each week. Also, around 2/3 are women. So, it isn't possible for us to dance without a bunch of role swapping. Even though I have them partner up in the workshop using a scatter mixer, so there is plenty of same-gender partnering even among the men, when I teach the swing in the very next exercise with the existing partners, there will be some (unrequested by me) shuffling and we have nearly entirely guys dancing with women and standing on the left, and women dancing with women with the more experienced person on the left. This has most of the new women learning the robin's role, save in the occasional two-beginner-women couple.
For a while I tried teaching the swing from both sides. It got awkward and uncomfortable for many of the guys (women didn't seem to have a problem with it), so I don't do that anymore. When I'm asked why we do larks and robins (it's rare that I am), these days I just point out the number of women and say that it's to facilitate role swapping, as otherwise we'd have too many sitting out.
Still, I feel bad about not giving the newbies exposure to both sides of the swing. The women typically do learn both sides after they're confident, a few evenings later, but it's rare for guys to dance the robin (maybe once a night someone does). Some of the dancers are religious conservatives, especially the younger ones (homeschoolers, some of them), so I don't push it. Still, if we had some mechanism that would make it more socially comfortable, I'd be very interested in learning about it. (Hmm. Maybe if I had a dance with a larks swing and a partner swing, some of my larks would swap...! Ok, not going that far with this group. Not my job to tell them what to like.)
So, I guess this is something like your, "unless you have a preference, whoever is standing on the right of your partnership is the robin for now", with nearly everyone having a preference for the traditional role and some of the experienced women swapping for the good of the dance.
BUT, when we had a college dance in 2022-2023, the story was totally different. There, we had guys comfortably swapping, just like in many Northern, urban, community dances. I just taught people in whatever role they were standing in, and I taught both sides. I didn't tell them to learn one role before learning the other. Most swapped a lot and did great. The students mostly taught each other after that, and I did occasionally hear the advice that someone who was less coordinated should stick to a role until they got it basically down. But, college students are young enough that their brains are still sponges and they learn fast. It might not work so well for older newbies.
So, I think the answer lies in how much social inertia there is in your group, and what direction it's in.
--jh--