You may already be familiar with the 'Pareto Principle' (also known as the 80/20 Rule), named after the 19th century Italian economist who first noticed the phenomenon that 80% of all results tend to be produced by 20% of all efforts.
So the theory goes that 20% of your clients provide 80% of your turnover. 80% of your problems come from just 20% of your experiences and so on. Have a look at your sales figures and think about your experiences, both business and personal - does this theory ring true for you?
You can also extend the rule by examining what is happening once you have identified the critical 20% - within that 20% of time, when does the 80% outcome occur? During the first 20%? The last? Or in the middle? Can you refine your use of time further?
This is a continual process of noticing what gets you results. Don't just do something and forget about it - evaluate what you have done and reflect on what works.
People often ask me for examples where this might apply. A very good example is marketing. Someone I know examined which of the pages on his website were getting the most hits and discovered his portfolio page was most popular. He made that page his home page, to reduce the effort visitors had to make to reach the information they wanted, and increased the number of hits and enquiries made about his services. Simple but very effective.
If the Pareto Principle works, then having found which 20% is producing the 80% results, you may never have to worry about time management courses again!