Interesting question ...
A quick peek into Groener ("Die Deutschen Kriegsschiffe 1815-1945") indicates that 3-shaft propulsion was a feature of German capital ship designs starting with the Kaiser Friedrich III class of pre-dreadnoughts dating back to 1895 (laying down of first ship in class). This trend appear to have continued (with the sole exception of Prinzregent Luitpold with 2-shafts) all the way to the Bismarck class. The post-Bismarck design projects (H, J, K, L, M, N) had 3-shaft diesel propulsion, while the later designs (H42, H43, H44) had 4-shafts.
The German WW1 battle-cruisers (all the way through the uncompleted Mackensen and Ersatz Yorck designs) featured 4-shaft propulsion.
The post-WW1 diesel powered "pocket battleships" (Graf Spee, Deutschland) featured two shafts. The WW2 era "light battleships" (Scharnhorst, Gneisenau) and the heavy cruisers (Bluecher, Hipper Prinz Eugen) all featured three shafts.
Byron