This is why I prefer ordering with the app, they see the whole list of what you want and don't have to go through the mental effort of wondering how much of what to use as they don't know how many stuffings you want.
The whole point is to get them to overstuff it though. That's why you make it seem at first like you're not going to want much but then you ask for everything you can possibly get, one by one.
"A bowl"
"White rice"
"Black beans"
"Oh yeah, some veggies too"
"Actually maybe let's add some sofritas to that"
etc.
That said -- I usually go with a bowl instead of burrito, makes their life and my life easier
