I have a family friend who chose a realtor for the same reason. He said that because she sells a million dollar home every couple of weeks, she would be best to sell his home (also over a million dollars). After a couple of months, he cancelled the listing and went with someone else.
I think people should meet with several agents and go with the one that feels like the best fit. The agent should be honest and professional, have a good plan for marketing and selling the property, and have enough experience to get the job done. That doesnt always mean $20m of sales per year.
People should also ask themselves this question: who will you get the most attention from -- a realtor who has a new listing every week, or a realtor for whom your listing will make or break his month? I think the person who needs it more is going to do more to earn your business, keep you happy, and sell your home quicker.