I was inside a busy McDonalds along a major freeway last year and someone in the kitchen yelled "I have paused the app, stop taking orders at the counter and drive thru". I gather from the staff that at times they got swamped with orders JUST from the app, greater than the capacity of their cooking operation to prepare in a reasonable time and they have to pause it for 30 or 40 minutes. They did resume drive up and walkup orders in about 10 minutes.