I have worked and been sizing for GK for a little under three years. I was actually the first cheer rep ever hired. Anyway, that aside - I feel pretty confident that I can eye ball a kid who is up next for sizing and be pretty dead on. I am not 100%, but out of 100 kids, I would say I am right on at about 85 of them from eyeball alone. I had this one mom come with her kid to get a sized. I gave her what I thought was her size and she went to the bathroom to change into it. The mom came back out with her daughter (who was probably 12-13ish) and said that it didnt fit. She said the crop top was so tight her daughter could barely breathe and that it felt red marks indented in her skin it was so tight. The daughter was almost in TEARS, mind you. Anyway, I was shocked that I would have gave someone a uniform THAT mis-judged, but regardless, the mom asked for the next size up, and I catered to it. The daughter came out and the skirt was so long it looked like a Rec Cheerleading Skirt and the top was BARELY staying on her shoulders. I tried explaining to the mom that this size was OBVIOUSLY too big and showed her the key points of where we wanted it to be nice and fit. This particular gyms uniform was a custom design and had some cut outs in the back and shoulder so it needed to fit nice around the shoulders. I also explained about the skirt being too loose as it was going to almost fall below her hips. This mom was going around to other parents saying that her daughter got mis-sized, and its too tight she can't breathe, etc. I finally told this mom that I would pay for it if it didnt fit. She went and put on the one that was "cutting off circulation and leaving red marks" and it fit beautifully.
I hope I never come off ignorant at sizings. Not to brag, but typically parents that come to me and say "this is too small" or "I need this shortened or lengthened" I entertain them and allow their daughter to try the next size up. Typically they are end up saying "You were right, I am sorry" I would hope I would never ignore a parent and it was like "pulling teeth" to get anything done. I will say though, as I know many parents, esp. ones on here, know what they are talking about, I feel I have delt with ones that have no idea. GK Uniforms DO fit like a glove as someone else mentioned. Our sizers are TOP NOTCH when it comes to sizing and how they actually fit.
I must say, gym owners are very trustworthy of me and typically have my back with decisions. When I am wrong, Ill own up to it, but me personally, I have a pretty good track record with my sizings.