The times that I've made the least progress on writing was when I was trying to do it on the side or as a hobby. This isn't because of the relative amount of time I devoted to it. It was because I treated it as something I would try to fit in, and it never did. I could always find something else to do.

Links:

Writing Practice (podcast by Aliya S. King) - Episode 12 is very focussed on morning schedulesCal Newport's Time Block Planner Method

Transcript