Saddlefitter: I agree. One needs to be ready to change the plan given the horse you're riding on a given day. But starting with a plan gives method and meaning to the work.
I, too, log each ride. I have a calendar with boxes large enough to write in my unique dressage shorthand after each ride. Exercises we did and how the horse felt. It helps to be able to look back and see what we did and how it went...even years later.
set-backs are proof of what doesn't work, people who speak negativity are just that people.....not prophets, sometimes it rains, sometimes it snows, sometimes it is too hot, but like the mail... dressage must go on...!!