Note, my question wasn't specific to crafting items, but asking about the efficiency bonus in general. Specifically, relating to Jasea's Archaeology (gathering skill) efficiency bonus on missions.
I don't see this being the case. I click through Archaeology on each companion (I have 4+the droid, now) and every single one has the exact same time on each mission. From Pierce with 200 affection, Jasea (bonus to eff) with just over 2k affection, to Vette with only 3k eff.
So, from my perspective, either the bonuses of the individual companions is global for all, or there's a bug somewhere.
I don't know how it works for you, but efficiency works that way for me and I have specifically tested it. I don't think
affection and efficiency effects time needed to craft, I am completely sure
it reduces the time to complete these tasks.