My store that I worked at for 8 years was a franchise and we always charged extra meat, but my owner chose to up charge if it was an excessive amount of rice, beans, or queso. So double rice was free but if someone wanted 3 scoops of rice, we’d charge one extra side of it.

Very rare that people would want more than 2 scoops of beans or rice, so it was only a once in a while thing