100% my experience. You would need a combination of the right project for the right client where the affect on bottom line is both observable and observed.

Most of companies who are considering a consultant are organizationally incapable of telling you how much money is saved or generated. On the other hand, most companies have a sense for how much an hour of work should cost and would be comfortable discussing the project in those terms. So you'd seriously be limiting your options if you focused on the former.