Business owners often do not need or cannot afford a CFO on a full-time basis but may prefer to have regular discussions with someone on strategy and plans while working towards long-term goals. In addition, CEOs may want to hand off some back-office tasks to experienced executives who can take control of finance, legal, IT, etc., whilst concentrating on what they are good at.
You pay for the full-time knowledge of a CFO but at a pro-rated CFO rate.