Photographer and Publisher David DuChemin describes his process and it sounds familiar:
“On a smaller scale my productivity has gone way up as I’ve transitioned from keeping a TO DO list to just putting stuff – even the smaller tasks – straight on the calendar. Putting it on a list says 'do this at some point' putting it on my calendar says 'do it now.' I still keep the list because that’s where things go before I put them on the calendar. But if I sit down on Sunday and think about what I need to do in the coming week, the stuff comes off the list and goes onto the calendar. I schedule it.”
With this system, he's written 9 books and 20 ebooks, while running a publishing and photo business, traveling around the world, and hosting workshops. This is the kind of stress test on a productivity system I could not duplicate.
Remember, worthwhile productivity systems exist to help you to work LESS and stress LESS, while making greater progress towards a better life, whatever that means to you specifically. It's not about just getting more done.
I may sound like a broken record on this topic, but it appears I'm in good company.