Ed Catmull, President of Pixar, writes extensively about the creative process Pixar goes through to develop films in his autobiography, Creativity, Inc. Stories start with an idea which gets pulled apart, developed, re-written, pulled apart again, re-written etc.*
"Early on, all of our movies suck...Pixar films are not good at first, and our job is to make them go...from suck to non-suck."
It was a stressful, time-consuming process but worked. A few films down the line (Toy Story, Toy Story 2 and 3, Monsters Inc etc) Pixar thought, wouldn't it be wonderful if they could skip all that angst and wasted development.
"This then became our goal - finalise the script before we start making the film. We were confident that locking in the story early would yield not just a phenomenal movie, but a cost-efficient production."
Great idea, so they set it in motion. The screen play was written, the film made. Trouble was, it didn't work. Test audiences found it confusing. Industry execs were lukewarm. It was clear that what worked on paper, in theory, didn't translate to the screen in practice.
So they went back to pulling it apart and re-writing, pulling apart and re-writing yet again, and the result was Finding Nemo. They've stuck to that process ever since.
If you want to write several books a year planning, and then sticking to the plan, seems essential - and well done you if you manage it. I've always been in awe of the productivity rates of some authors.
But just because some people do it, you shouldn't beat yourself up if that's not your way of working. Hey, you might not be producing 4 books or more a year but you're in the same company as Pixar.
*At a dinner party a few years back I was lucky enough to sit next to Doug Chamberlin who co-wrote the screenplay to Toy Story 2, and he told the the process was extraordinary and exhaustive. He also said that Pixar never employed the same screenwriters twice, I assume because the re-writing process was so draining they reckoned no scriptwriter could go through it a second time.
Creativity, Inc. by Ed Catmull
via Black Box Thinking by Matthew Syed