The convergence of Schwarz methods can be influenced by the geome- try of the decomposition, and therefore also the optimized parameters in optimized Schwarz methods depend on the geometry. We present a first study of this influence, which reveals that in contrast to results in the literature so far, where only the interface length is taken into account, the diameter of the subdomains can play an important role as well. The new estimate also includes the influence of lateral boundary conditions.