I've been working with Waves Tune on the last 2-3 songs I've done...trying to see how transparent it can be.
While they recommend strapping it across the whole track. When I tried that to see what it could do, I found that using it like that can do more harm than good....and then often when mixing down, you can get more artifacts in spots.
So I came up with my own approach, where I use it only in key spots where some help is needed on a note or two, and where the Waves Tune version is clearly the better choice than the untouched version, and where WT doesn't make it sound unnatural.
I also keep the correction on the soft-n-gentle side, because I don't like the sound of hard correction, never mind that extreme shit you hear in R&B music.
Then I blend those corrected spots with the rest of the untouched track.
IMO...it depends on the song really. I mean, if it's a more classic rocker, where the vocals are just belted out without any concern for purity of the melody...then the pitch correction is not needed, but with a flowing melody that might cover a couple of octaves...well shit, I'm a baritone and my range isn't super wide, yet I may have a song with a vocal melody that hits some high notes that are at my outer limit, and then I could use a little help.
My approach to pitch correction is similar to using EQ...do as little as needed...and like minimal EQ on well recorded audio tracks, pitch correction always works best on well sung vocal tracks...and not when trying to pitch-correct a total pile of doo doo.
Anyway...in sparse, soft-n-gentle use....I like Waves Tune overall as a tool.