Like others have said, you do have the option to pick up your order and leave. If you choose to dine in, I believe the guidelines say you need to stay at least 15 minutes. And definitely remember to check the restroom either way.
@HoomanShopper: If I remember correctly, I think it is for the Online Shops that you need the description of the employee who hands you the order instead of the cashier (because you pay online or via the app, so you don't have to pay a cashier when you arrive at the store). Since you still have to pay for your order when you arrive at the restaurant for the Phone shops, I think the questionnaire asks for the cashier description...? But I could be wrong...it's been a while since I've done one of these shops, since they keep being taken off the board by shoppers at base pay.