You mean Bf109 I think. The P-51 started 3 and then moved to 4. Ditto P-47. FW-190 and F6F stayed at 3 whole time afaik. Tempest started with 4. So it varied. But there is a trend of the early (1939) designs to have 3 and the late (1944) designs to have 4. I guess available power from the engine plays a big role, as engines got more powerful they started fitting 4 blades. Using the extra power on 3 blades would require longer blades (which is problematic), spinning them faster (again, problematic as tips reach sound barrier) or increasing the pitch (I guess there are aerodynamic limits for that).