There are some very commonly used statements where we always use "at"to refer to the location of something or someone and never use "in". Here are some examples:
When you stay at a hotel on the beach you are literally on the beach when you walk out of the beach side of your hotel.
Tips for keeping the weight off for good. Here are a few tips to help you stay at your goal weight: Don't go overboard.
She prefers to stay at home.
My question "is it because of some rules of grammar rules that these sentences follow "or "just because the native speakers say it that way"??