Some restaurants offer all-you-can-eat buffets consisting of both vegetarian/vegan and non-vegetarian dishes (e.g., many Asian-style restaurants, several US chains, hotel breakfasts). It's unclear to me whether buying access to such a buffet and exclusively taking the vegetarian/vegan options increases demand for animal products regardless. I guess the answer depends on whether restaurants decide on amounts of animal products to cook depending on exactly what was taken by customers vs the pure number of customers buying the buffet.
Does anyone know the specifics of how such restaurants typically operate? How can one tell whether a certain offering is likely acceptable? Is it useful to tell staff in advance that one will only take veg*an food?