I applied this principle when I was mother to many small children and still do. Some days the 3 most important things got done smoothly and I got to make a newer, possibly more fun list (e.g. phone a friend, bake cookies...) And on bad days, I at least could look at the end of the day at 3 things is did get done. Without a plan, you are just careening from crisis to crisis and at the end of the day possibly zero things really got done.