The thing is "10x writers" (in terms of volume, at least) aren't uncommon at all. My best day while writing my second novel I wrote ~11k words. That was <6 hour

The thing is "10x writers" (in terms of volume, at least) aren't uncommon at all. My best day while writing my second novel I wrote ~11k words. That was <6 hours of writing. My biggest challenge was 1) maintaining focus, 2) I have other things to do. Most writers can write quite fast if they really have to, but given the income distribution it rarely seems worth it: If you make little, it becomes a labour of love and you're more interested in producing something you can be proud of; if you make a lot, the pressure to churn it out at high speed lessens. And while there are some in-between who need to churn things out fast because they depend on the income, they are few (incidentally there seems to be only poor correlation between rate of writing and income per book). And so the speed people write at seems to often depend more on whether people choose to because they see it as a job to get done vs art/a personal project.