Mostly I do display set ups and display repairs and I sort of like doing Walmart Stores. For me hourly pay is a must and I usually get travel time and mileage.
If I don't need staff or manager assistance work is quick and easy and staff and mangers are usually pretty pleasant. My success rate in Walmarts is 100% and usually under the allotted times when I have everything I need shipped to me.
That said if I need to rely on staff or if parts or inventory are at the store..
manager signature seems to take about 15 minutes
pulling merchandise from a back room at least 15 minutes
finding a display shipped more than 2 weeks before I'm there has taken 15 to 90 minutes
about one third of displays could not be found by me, the staff, or the managers
So you can see why I rarely take flat fees to do anything in a Walmart. Targets, Best Buys, and Costcos are much easier to work with.