* Definition of "special effects" is broad: What counts as a special effect? Simple things like camera tricks, editing techniques, or even makeup could be considered. Do we include CGI, practical effects, or both?
* The number of movies is vast: There are millions of movies made over the years, and new ones are released constantly. Tracking every single one would be a monumental task.
* Data is incomplete: Not all movie databases track the use of specific techniques like special effects. Even if they did, many older films might not have detailed records available.
Instead of a specific number, consider these points:
* Special effects are almost ubiquitous: Even simple movies likely utilize some form of special effects, even if they're just basic editing techniques.
* The use of special effects has increased significantly: With advancements in technology, special effects are more accessible and common in movies, especially in big-budget productions.
While a precise number is unattainable, it's safe to say that a huge majority of movies utilize special effects in some form.