Isn't it a very low percent? We use 5% of the cheese's weight in sodium citrate to make the cheddar sauce for our cheesy, beefy burritos at home.

Unless you mean the milk (or whatever substitute) it's emulsified in?

(We were able to cut down on the milk and get a much stronger cheddar flavor compared to the previous cheese, milk, and corn starch version we used, but we still use 60% of the cheese's weight in milk which does of course still dilute it a bit.)

Considering the minimum for calling it American cheese is 51% cheese, and we end up around 60% cheese, I don't think the concentration is too low. You could just use cheddar on it's own, but I think for both burgers and burritos the emulsified version is worth the milk dilution. Especially with the cheese sauce being nicely heated and spiced up with chili and a few other things.

I used to think American cheese was ridiculous, too, before I watched an Adam Ragusea video about why sauces break, wherein he had a part about cheese sauces, and demonstrated the "natural" way to get the emulsifying salt from lemon juice by heating it mixed with baking soda and tasting until it's no longer tart... I think it was?

Either way we tried a few times, it was difficult, but then I just bought a small container of sodium citrate to skip that step. Immediately changed my mind about emulsifiers after trying it. It was just nice. A really silky, awesome sauce.