Photonic topological insulators (TIs), periodic structures with a band gap in the bulk but gapless dispersion at the edges, possess the unique ability to guide light around defects and sharp turns without scattering. Such topological protection of light propagation provides an exciting new platform for on-chip low-threshold lasing, robust long-range quantum information and energy transfer, unidirectional emission from spin-polarized quantum states, low-dimensional and only ~12% at the majority-trivial corner. Thus, in devices requiring sharply bent topological interfaces, such as topological resonators, we present a new design rule for choosing corner geometries to optimize robustness to disorder.