If its for the handful of adult males shop,this is on the first page of the guidelines:
"Do not complete two shops within the same meal period on the same day for Five Guys or your shops will be invalid and you will not be paid or reimbursed."
For the chicken ones there are four different time ranges listed in the guidelines. You could theoretically do four of them in a day. Then for the burger shops you can do one before 4 and one after 4. So, that would be one lunch shop and one dinner or late night shop.