I'm late getting in on this, but I generally dislike writing so I don't spend much time doing it. I also get tired of working on a page. I get (what I think at the time is) a great idea!! - start a page - and then get bored with it, or change my mind about it being a great idea. I have a bunch of them started that I may never finish.
Then, all of a sudden I get the urge to write - so it's sporadic. Can't give you a good answer on the time question.
I'd rather be creating designs but I can't live on just doing that. If no one sees what I've made, no one will ever buy it. I don't usually enjoy the writing part of it all that much. But the nice atmosphere here at Wizzley brings me back to at least try.