There's a balance though - 20/30 is not a problem but I've easily waited close to an hour in the Grill Pit on a not particularly busy lunchtime. One of the big problems is the unwillingness to have more than one person on waiting.
Last time we went in, we had pre booked a table for ten. There was only one other table occupied when we arrived. We ordered straight away, nothing complicated and it took one and a half hours for the food to arrive...never again!