I find it ironic that ditching my desk job has actually made my day more complex. For the longest time (almost a year now?) I didn't realize that. When I worked away from home, I was generally in one of two modes: long-term and short-term. And my day was very basic. Get in, get settled, and work on my main, long-term project. Sometimes the phone would ring and I would need to drop everything and fight some fire. Then, when all we had was some wisps of smoke, I would return to the long-term project. And that was how I worked best, doing one thing until it was done, then moving on. You don't need a Daytimer when your life works like that.
For the most part, being a SAHD isn't like that. Sure, there are times when you spend the whole day sodding the yard or what have you, but most of the time your tasks (well, my tasks, anyway) are done in these little chunks. Get the laundry going. Pay the bills. Make a phone call. Run some errand.
Big deal, you say. These are just small long-term projects. Do them in order. Well. Here's the rub. Have you ever noticed how dogs will often make several little circles before lying down? I do that before getting to work. It can take minutes or hours or days (depending on how complex and/or unpleasant the task might be). Not much of an issue if you can then sit down and plug away for hours or days at a time. But when doing myriads of small tasks? Oy. Prepping (or, more correctly, psyching yourself up for) a day to do something that might require twenty minutes is generally not efficient.