Not very often. I've learned from past experience that it's best and most efficient to spend more time rehearsing the performance and recording clean/solid takes than it is to try and "fix" something which isn't so great. In the end, it will save you time and help you not to lean on the technology for a great recording. I use pitch correction software for very minor tweaks, most times for corrections that are almost imperceptible, but tighten everything up for that extra little polish on a production. I have used Auto-Tune for an intentional special effect before, which can be very effective if done correctly. At the beginning of "Stand" on 'The Takeover EP', there's a heavy pitch-correcting effect generated by using fast/selective tuning. The vocal intro of that track is meant to have a very digital "lo-fi" sort of dynamic to it. In the end, I eventually felt it sounded more just like overt tuning rather than a sound effect. When I remixed the song for 'The Takeover' full-length album the Auto-Tune was taken off to better serve the part. Simply put, pitch correction can be a very valuable tool as long as it's not abused.
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