I recommend prospective franchisees take a look at Empire Builders which is a series of videos highlighting successful multi-unit franchisees.
Most of the prospective franchisees that come to see me are seeking to purchase a single franchise. Many of them dream of becoming a multi-unit owners but usually lack the capital (at least initially) to make that a reality. It's interesting to hear from multi-unit owners who have been able to harness the power of the franchising model and achieve great success. It is easier said than done.
There are some great videos in the series covering topics such as: