In the Qualifying you would be normal to see a land triple, a land blind, a water blind and water triple the distances are usually under 300 yds on these but there is no limitation in the rules. The marking tests usually have one retired gun. The series may be combined, so you may have a land triple in conjunction with a land blind.
In the All Age stakes (Open & Amateur) there is usually a land and a water marking series as well as a land and a water blind series. Because the competition is stiffer than the Qualifying, the distances are longer and there are more factors in All Age stakes. The judging is much tighter at this stake. On blinds there are often poison birds, scented points and the dog should be able to be handled on and off of points with little effort. The dog should be able to drive tight past the short bird to the long punch bird.
I believe the Retriever News site has some videos and diagrams of past Nationals that give some idea of how tough the All Age tests can be. A search of YouTube should also come up with some videos of individual tests at a trial. The best thing to do is to go watch one.