@Jorg_
There are so many 2 tops that you will not have to wait too long even if you arrive at peak time. The norm for booking in the MDR is when you want a large group to be seated together, say 6-10. Above 10 you would have to book as they have to move furniture.
I have been in an MDR when a group of 16 just turned up "demanding" a single table. It took a long time to get it "sorted"!! With lots of ill feeling on both sides, not that the Maître d' and Restaurant Manager lost their cool!!