I failed the strength check despite being a paladin and using inspiration. I never saw him again even after getting through nearly all of act 2. I’ve asked this before, maybe even in this community, but no one gave a concrete answer, likely because the game was still new.
I think only Lae’zel and Shadowheart really have multiple chances.
Gale, Karlach, and Astarian only show up in a single place.
Wyll has a couple of places, depending. If you don’t recruit right away, he’ll show up at camp if you recruit Karlach.