As for thinking time versus writing time, well, that's up to you. But - and I wish it were otherwise - books don't get written by thinking about them, they get written by writing them. And that's when you make discoveries about what you're writing. That's when you get the happy accidents.
I would have none of that rigid circumspect charity which is never done without scrutiny, and which always mistrusts the truth of the necessities laid open to it.