I personally feel, this is the way to have the deepest connection with the characters and experience in the story, be it a movie or a novel. So planning out a novel can become more than initially intended. How far can you go? What is, reasonable, for novice and experienced writers?
Idk, I have big dreams but I find I write best if I give myself more modest goals. My Masterpiece (sarcasm) is stuck halfway through act I, so I wrote a short story based on a prompt I gave myself (young woman and serial killer stuck on a spaceship). I didn’t mind that my characters were cardboard or I was using every trope available to write a formulaic story, at least I was getting good practice in and getting a story out there. now I’m working on another short story where I am exploring one element of my Masterpiece (loss of a loved one). So I guess my advice (worth what you paid for!) is don’t be afraid to take small steps towards big dreams.