Sorry if my earlier message seemed over-simplified- I was on my way to a meeting. But, over the course of more than 30 years of running businesses, that's how I approach strategic planning. There are many different calendars, and a number of people have mentioned some good ones here. In my opinion, though, you really have to track time in terms of engineering, marketing, sales, and administration, and you need to have a very good sense of priorities.
The tool matters less than your planning.