They only do cask beer in wooden kilderkins, which they give nine days shelf life on filling. They don't do any more cask beers as they need these to turn over fast.
When I stayed in Bamberg I was surprised when I got back to the hotel to be offered my complementary bottle of beer! I'd had quite enough already, but how could I say no?
Beers with Brett as a secondary yeast I normally leave for two months. I suspect the last slow bubbles are the beer going flat, so I left the last only a month and it's been fine.