^^^^ Thanks for the information on the 1929 Championships of Berlin tournament. It's very difficult to find the details of German/Austrian/Swiss tournaments in the early 1920s because those countries' players were barred from most international competitions from circa 1919-27 because of World War One.
As for European tournaments in general, during that era most tournaments were usually held at the same time in the same place each year. A schedule of, say, British or German tournaments would be published at the beginning of the season, or even earlier, and kept to throughout the year.
This hadn't necessarily been the practice at the dawn of lawn tennis, but as the number of tournaments grew and grew, it was realised that a more or less fixed schedule would make a great deal of sense from an organisational point of view in particular.