Too long… Too short… This one is just right.
I tend to measure from shoulder to opposite out stretched arm plus several inches. Make sense when you use you body to measure as it is hard to misplace.
I have a very flowy (is that even a word?) technique, so I do prefer longer string AND the beauty of longer string, it can be made shorter… same can’t be said the other way…
For my responsive throw, belly button as I just carry it with me for throwing when doing other things (walking, shopping, at work, whenever my ADD kicks in)
Long is good for about everything
I’m 6’6", I need all the length I can get!
Un-cut Toxics, are perfect for me. Also Chaos strings are crazy long.
6’6 at age 16?! Flip son, what do they feed you? :o
I tend to go for shorter myself. An inch or two bellow the old belly button (I’m 5’10, for reference) seems to be the sweet spot for me. Makes chopsticking a lot easier as well because you don’t have as much slack string lying around to get tangled in. 
I never adjust the string length, use whatever length the string comes in.
I prefer bit longer though, even though longer string can make my tricks bit slower, but the extra time can be useful for more precision.
I like shorter becAuse i can have more control over the yoyo, but longer for slacky whippy tricks
I live in Wisconsin. I eat a lot of meat, some carbs, and contrary to EVERYONE ON THE PLANETS THINKING, not too much cheese.
Also, I’m the tallest in my entire family. At least 4 gens back.
You don’t even WANNA know my shoe size!!!
I get YYE Poly and don’t trim it. I am 5 foot, 9.5/10 inches, so it’s close to being around my chest.
I tend to like longer strings, so I can do more tech (my favorite trick type) easily, due to it not being so crammed in.
I like to play Long because it gives me more room to do more technical tricks.
Fixed.
Right in between. Perfection
Since I am 4’4" I play my strings a bit longer. Belly button length doesn’t give me enough string to do certain slacks and tech