There are two approaches that I commonly seen taken to resourcing projects:
As much as I'd like to say that the former works well in a setting like a supermarket, I can't get on board. Having spent most of my teen years working at Wegmans, I find the latter approach has merit, no matter what the work entails.
I started at Wegmans pushing carts and ringing up customers. Through my several years there, I did everything from stocking shelves to managing disgruntled customers at the customer service desk to making drinks in the coffee shop. Somewhere along the line, I became a Front End Coordinator, scheduling cashiers for the day and addressing any issues during a customer's checkout.
I was always learning, and that variety kept me going. If it wasn't for that, I don't know that I would have stayed as long. I still apply what I learned at Wegmans to my life and work today.
All in all, I believe that people tend to stick around longer when they feel challenged in their job and see their efforts moving them forward. In that way, I see no difference between shifting an employee from cashier to customer service and assigning a designer on their first e-commerce project.