Yes indeed and I am of course aware of that. Going back to Condor, they have a number of rows with just that little bit more leg room. When booking Premium the seat selection engine offers only row 1 until such a time row 2 is required, and so on, until all YP seats are allocated. If for instance at a given time (I don't know what criteria they use for this) some of these YP rows remain free and the Y cabin is full, then those remaining YP rows are released for sale as Y. Yes it means that some lucky people will have the extra 2 inches or so but they get none of the other extras. The airline therefore retains a certain amount of flexibility with the cabin configuration.