billythekid

I'd say yes-- the plane you're 91 on wouldn't trigger the extra year on the 135/121 plane, but the 135/121 plane would trigger the extra year on the 91 plane.
Based on 135/121 rides are "more extensive" than 91 rides. If you look in the training center course descriptions (the documents approved by the FAA) they usually say a 61.58 says counts for an instrument competency check, full landing currency, biannual flight reviews etc.
so in theory, a 121 ride would cover the 61.58 since it would include a normal recurrent + all the super fancy stuff airline pilots do.
I see emails from people looking for 91 CRJ/Erj contract pilots--they usually specify either a yearly recurrent on another recurrent in the precious year with a CRJ/Erj within 2. Think of a regional guy who got hired/trained by a major---in year two, he could go contract on a 91 CRJ/Erj, based on his 737/airbus 121 initial.