How many people here DON'T use pitch correction in there mixes?

[grimtraveller]

go back and listen to the singers that are considered the greatest of all time such as say, Frank Sinatra or any of the jazz greats ..... or any of the rock and roll singers that are considered great (the ones before pitch correction became common) and you'll notice NONE of them sing every note dead-on pitch.

I think the important thing here is that there is dead on pitch, then varying degrees of "fractionally off pitch" mutating into "out of tune". When someone sings fractionally off pitch on the odd note here and there, then depending on the melodic sequence, how the words are sung, the vowel sounds and their length and where and how they fall, how close together the words are, etc, in the greater scheme of things with all the other instruments or backing/harmony vocals and volume balance, then it may not actually be noticeable. Most of the time, in the old days, it wasn't.
It's when slightly off notes are plentiful and regular in places where the vocal is exposed that it starts to slip into the realm of out of tune.

Yeah I don't see what the big deal is with just re-doing something. I understand time constraints and stuff, but if you're paying attention during tracking, shouldn't pitch problems show themselves pretty quickly?

Yes they should and 98% of the time, they do, but I've noticed on a few occasions over the years that they don't always. I'm not sure why. Sometimes, it's age. Sometimes it's tiredness. Sometimes, it actually does sound OK but then the next day, you hear it and think "how did I not catch this ?". It's happened to me a couple of times recently on the same song ! For the chorus bit, my friends and I were singing to an already tracked bass line and there are 2 or 3 variations on the melody that could work, though only one that I wanted. I could never remember the right one right off but when we did what I thought was the right one, it sounded OK. It wasn't until a week or so later when doing the harmony that I realized what we'd done was totally out. It took me a while to remember it but we've since retracked it properly.
In the same song, there was an 8 line sequence that I did and I thought it sounded pretty good. Four days later, I listened again and it was woefully out of tune ! I was listening in utter amazement. So I redid it and spent ages listening to every little nuance before I was satisfied.
I'm usually quite good at spotting off notes. It affects me like when the dentist blows cold air on sensitive nerves.