Alfred Hitchcock wasn't one to let things happen by chance in his films. It's fair to say that he had an idea of the look of the film — shot by shot — in place before the cameras ever rolled. He probably saw the actual shooting process as a nuisance.
Above are storyboard for the climax of Saboteur (I hope I don't need to include a spoiler warning for a movie made in the 1940s.) Compare the level of detail present in those panels to that of the one below, a short of crucial scene from Psycho.
There is a lot of rapid editing in the famous "shower scene" and it's surprising that few people notice.
Shower curtain=movie screen