For me it depends on the project and my motivation. I spent about 5-6 hrs yesterday and another 7 hrs today working on a single (king size; paper pieced) quilt. Because I'm used to spending large chunks of time sewing, it's hard for me to spend a mere 10-15 min. at a clip working on a machine piecing project. I can do that with hand quilting but not machine piecing.
After a few weeks and only a few chuncks of the above type available time, I'm only 15 blocks into a 72 block quilt! Wowzer!
If you've made that amount of progress in that short period of time...kudos to you!