We always did a similar game -- try to guess what trailer it is before it plays the title. Usually the adept moviegoers will have it in the first few seconds.
After working in a major chain theater and making up prints of movies, I have found that EVERY movie has either 5 or 6 trailers on it. Now, that can change once the movies start to come out and trailers are removed, but every movie starts with this many, usually 6.
However, I have noticed this is different at independent movie theaters, so maybe it depends more on the theater than on the movie.