Sorry, I do airport shops for an "invitation only" MSC that uses a small cadre of shoppers to do all of their shops at a number of airports around the US. Their client insists on using the same shoppers on 60 day rotations, but with different shop lists for each shopper such that the roration for any one shop is about 90 days. I do routes of 18-25 shops at a time at each of two large airports, every 60 days. Yes, shoppers must commit to repeated cycles of shops.
If you search "airport" and all dates, you will find lengthy discussions of other ways of getting airport shops than committing to a regular routine of long circuits. The way they are handled vairies by client type. As far as I can tell, only the ones where the airport management company is the client require this sort of ongoing commitment.
Based in MD, near DC
Shopping from the Carolinas to New York
Have video cam; will travel
Poor customer service? Don't get mad; get video.