There are all sorts of studies, lists, and Facebook links to how much time (daily) famous authors spent writing. Modern writers post their stats for writing and editing. I doubt I'm the norm, as I write in short stints. Very short stints. Twenty minutes at a time, if I'm lucky. I could claim that it's because I have work, marking, volunteer responsibilities, a new baby, and a husband, but that's not the reason. With editing, I'm far too impatient to plod through grammar for long lengths of time. With writing, however, I write scenes, then need plenty of time to daydream up the next one. I will sit in a chair and think. Lay on my bed. Read for inspiration.

My husband will say, "What are you doing?"
"Writing," I'll reply.
In response, I'll get the oddest looks.

Of course, sometimes I can do 5-6 short writing stints in a day. That adds up. Then the produced pages multiply. It's quite nice to see. I can't compare myself to other authors, monitoring their progress against mine. I do what works for me.