I'd love to hear the before and after versions of this session to know what (in your mind ) constitutes a need for "tweaking". To what bar are you holding these artists. I don't think 8 hour per tune is that off the charts. Try 8 hours on just one vocal....(shoot me now) that vocal being the best comp of 5 tracks.....she sucks. she payed cash up front though(actually a nice gal, you kinda rooted for her, but the tracks were TORTURE)
One mans "tightening up" is anothers sterilization.
That being said (puts gun back in holster

:
I've had to do way too much of just the same thing for some "trash for cash" clients.
Mind numbing work when it's "turd polishing for dollars"
thankfully, that kinda work won't be falling in our laps much more (by choice)
I spend alot of time that I know other guys would just take the money and run on because I refuse to let crap out with my name on it. As for really tweezy drum edits (tightening up) I'll often copy the track and do a second version with some creative tightening/retriggering/ low fi ing that I will discreetly run by the powers that be....kinda like:
"I just thought I'd try a couple things for fun" Often times they'll jump for joy....I only do that when I've been given some room to move as the Producer, otherwise I think it's pretty presumptious to do any deep editing. It's your opinion really. (but , being the producer,that's your gig at times)
One mans "Raw and loose" is anothers Crap.
I always have to "check myself" and ask if what I'm doing is making the artist into something they're not (or could ever be) And that could include tightening/tuning the traks.