mechanic buff duration card

I tested with a friend using Wild Hunter's Call of the Wild buff a little while ago. I don't remember all the details exactly, but from what I do remember, despite us both using mech cards, and his mech card being higher, Call of the Wild disappeared at the same time for the both of us, the time it would last if my mech card was the one that affected it. I distinctly remember it working on party members who receive your buffs, because then we tested Bishop's HS using Buff Mastery because I thought that maybe they changed Buff Mastery for mages, but no, the effect of Buff Mastery is still only for yourself.