It makes no difference when a movie comes out, only that its good.

The biggest difference is when they put hype on a release date to get peoples interest and then the movie is 'mentaly fixed' to a date, that if it passes and one didnt get a chance or motovation to see it at that time, they then think, "what was the big deal about it anyway", and then they drop the movie from their memory and never even look for the disc.

Saying that other movies affect it, is like saying that 1979 had way too many awesome movies to see in one year.
..(or staying up and watching them back to back with no sleep)