If you aren't getting enough done in your day--and who is?--try this time management technique.Not all hours are created equal. Some hours produce more net value–for you, your customers and your firm–than others. As my old partner liked to say, "Some of my hours are priceless and some of them are worthless."In looking at the most effective executives, leaders and business owners I know, I notice many of them are very careful with their time. This includes the appointments they set or take, the meetings they have, organizations to which they belong and the activities they fill their day with.Look at your appointment calendar from last week.