It's always fascinating with me to see how different shows utilize their child actors. I read somewhere that Sarah Charles Lewis (Winnie Foster in Tuck Everlasting) had understudies, but they never had a chance to go on before the show closed, and she therefore did all eight performances every week. I wouldn't call Winnie the most demanding child role ever, but "Good Girl Winnie Foster" is a pretty tough song to sing, especially when your voice is in that in-between phase when it's starting to change but hasn't quite changed yet. Yet Lulu in Waitress is on stage for maybe five minutes and has at least two actresses at any given time.
"I think that when a movie says it was 'based on a true story,' oh, it happened - just with uglier people." - Peanut Walker, Shucked