At the beginning of each semester, I always have high hopes for what I will be able to do in my classes. I have ambitious plans about have I will make things better. Maybe add demos or videos, or perhaps integrate in some of the modern literature to basic courses. Once the reality of the semester hits, many of those plans go by the wayside, and I mostly stick with the tried and true, updated each year for clarity and with better examples.
It is worse for a new course. Before I start prepping, I have all these goals about what I want to do. But then the reality of just how much work prepping a new course is hits, and I just try to make it as good as I can and still stay on top of things. For my first class, I had a whole bunch of lectures prepped ahead of time, and I still barely managed to be two lectures ahead of the class (so I could post notes in advance of lecture).
I am better about time management now, but it is still a struggle to prep lectures efficiently, especially because the first time through, I have no idea how quickly the class will move through the material. With a year in a course under my belt, it is easier to make timing adjustments on the fly, depending on how the class goes.