Scan the code at the counter and you have a place in line and a live estimate on your own phone. Then go do something else until it’s nearly your turn.
You can't plan around a wait nobody will put a number on, so you give up the hour whether the wait needs it or not. That is the part QueueDrop removes.
From scanning the code to walking back in, this is the whole of it.
Queue apps normally trade your place in line for something. This one doesn't ask.