Well, a friend of mine that screenwrites for a living says that it is essentially 45 seconds/one minute screentime per page depending on the author. If the author [like Bloch] describes at least half the time, leaving the other half dialogue, it works out pretty much as planned. Also, in general many books written pre-70s aren’t more than 250 pages - the 500 page blockbuster is more of a modern entity. I think if I look in my bookshelves at my books, a serious majority of them are sf/fantasy and other fiction pre 70 and under 250 pages. Many of them run about 150-175 pages.
Just as a wild example…pp 37[i think 1 page falls under fair use=)]
Then she closed her door and locked it. She could hear his retreating footsteps, then the telltale click as he entered the office next door.
She didn’t hear him when he left; her attention had immediately been occupied by the duty of unpacking. She got out her pajamas, her slippers, a jar of cold cream, a toothbrush and toothpaste. Then she rummaged through the big suitcase looking for the dress she planned to wear tomorrow when she saw Sam. That would have to be put up now, to hang out the wrinkles. Nothing must be out of place tomorrow.
Nothing must be out of place —
All at once she didn’t feel seven feet tall anymore. Or was the change really so sudden? Hadn’t it started when Mr Bates got so hysterical back there at the house?
I think perhaps all of us go a little crazy at times.
Mary Crane cleared a place for herself on the bed and sat down.
Yes, it was true. All of us go a little crazy at times. Just as she had gone crazy yesterday afternoon when she saw that money on her desk.
And she had been crazy to think she could get away with what she planned. It had all seemed like a dream come true, and that’s what it was. A dream. A crazy dream. She knew it now.
The italic line ‘I think perhaps all of us go a little crazy at times’ in the movie she heard in her head as she was rummaging around thinking and getting her stuff for the shower - that was a line Norman said when they were talking while having dinner. The hearing Norman sounds were handled by having the Norman sounds in the background as she got her stuff out of the suitcase. Here is an entire page that was handled by about a minute of screen action and sound effects. Her mental state was reflected in her expressions and movements, small hesitations, looking thoughtful and so forth…very well directed by Hitch. He did sort of make the command decision to cut out Norman getting drunk and blacking out which is when Momma took over and killed Mary, he just showed Norman falling asleep. I think most of the cuts in the story he actually made were to accomodate the film censorship boards. At least they let him leave in the unmarried sexual affair=)