From Tom Peters Blog “The Single Most Important Thing”

Consider these Four Cardinal Principals:

1. Time is more important than money. (It is the only truly constrained resource.)
2. You = Your Calendar. (You are What You Spend Your Time On as much as … you are what you eat.)
3. “To-Don’ts” are as important, or more important, than “To-Dos.” (What’s not on the list is perhaps more important than what is.)
4. Your To-Do List must never be more than 4 items long. (You can have an “errands list” but the real To-Do List must never run beyond four.)

 What I really think he means here is that you should never have more than four top priorities. The Marine’s “Rule of 3” (never give a squad more than three objectives) is even more conservative, and perhaps more appropriate to startups. Finally, a successful project manager never gives a meeting more than three objectives.