Stacking Vocals and Timing question

When Stacking Vocals, should you edit every stacked vocal so every single phrase are perfectly in time? I keep reading various articles saying you should only edit the first and last words and leave the rest as it is. Other articles say that leaving the stacks off time with each other will make it sound more natural and you should never duplicate a track but always re-record.



I have read about this plugin called Vocal-Align but this seems to align them perfectly which is what I read you shouldn't do.