If I asked the question directly, I think it would be unanswerable, so I'm going to twist it a little.
Knowing what you know now, if you were an A&R guy hiring a someone to mix an album, what level of detail would you want/expect them to take it to?
I thought of this while mixing tonight where I rode a vocal and for a word and a half it was about .3dB too hot. I thought to myself, that doesn't really matter, but I turned it down to where I thought it should be. There a lots of times where people agonize of details that no one is ever going to notice or care about - I think. I know sometimes I have to balance this out with my client's budgets. I work fast, but still, correcting ever .3dB issue takes time and of course getting things to sit within +/-.1 db of perfect takes even more. In some cases I have clients who ask to record and mix 8 songs in two days. Of course when I'm mixing a song an hour, I'm not making .3db fader moves (unless it 's a super templated rhythm section mix and I get some time to work the vocal).
So if you were hiring a mix engineer, what level of detail would you expect? Is there a cumulative effect of obsessing over minutiae like a should the reverb time be 20. vs 2.1 seconds or pre of 42ms vs 50ms or pan the guitars to 9 and 3 or 8:30 and 3:30?
I would expect the song to sound great. You're getting hung up on unmusical details. If the mix sucks, you did a bad job. if I, as A&R, love the mix then I'm happy and the day is a success. Mixing 6 songs in one day and making them all sound ok with an asterick doens't go far. I ,A&R, will find someone who CAN mix all six well in one day.