Marketing Mentor Ilise Benun points out yet another reason not to charge by the hour: As you get better at what you do, you do it more quickly and more efficiently. This makes your work more valuable to your clients. If you take less time, you will make less money, which makes no sense at all. That's why it can make much more sense to craft proposals on a per-project basis. If you do, continue to track your hours to aid in estimating fees for future projects.