We are told as writers that we must write every day. I do this if you count blogging, and all the other hundreds of things I do each day. I write grocery lists, to do lists, letters, emails, notes of things I want to remember, checks, and ideas that come to me. I try to write, as in write part of a book or other project, each day, but some days are too hectic and there are too many outside errands to do.
Still, I consider it "writing" or working on writing when I'm plotting ideas in my head. I may be washing dishes or loading the washing machine, but my thoughts are on a story line. That's the advantage of being a writer. You can do it anywhere, anytime.
Ideas come to me in spurts. There are dry spells, that really aren't that dry, just too busy to sit down and do it. Then there are days when my brain won't shut off and I have to sit down and start typing.
Many days I wish the household chores and errands would go away and I could devote the whole day to writing. But it's good to get up once in a while and move around too.
