I have no idea how anyone, if such a person exists (and I'm sure they do), would have had the patience to do this at full stamina cost. Twice over, for each account. With even worse skillup rates.
I always just never bothered even using them because the effort to skill them up was too much work and I would've been annoyed to only finish one account and find out how great they are, and then have to do it all over again.
Now I don't even have to stone to skill them at co-op's half-stam cost, it's fantastic – Krishna and Vishnu are done on both, Sarasvati is next. And with new Saras out in JP, Krishna and Vishnu can't be far behind. And Krishna may get a little more hype than Saras did, since he's not outdone by a You-Yu-type monster – here's hoping he runs TPAs, for AAres as star sub. (Vishnu may be great too, but since it's still UUVOs and not Awokens I expect he'll remain a better sub than leader).
All praise be to co-op.