Considering the immense applicability of Photonic Crystals (PhC) in Photonic Integrated Circuits, this work optimizes some bending configurations of PhC Waveguides (PhCWs), which otherwise incur significant losses. Here, four different bending angles, namely – 30°, 60°, 90°, and 120°, in a silicon based triangular lattice holes-in-slab PhCWs have been considered for the optimization. In order to keep the optimization attributes minimum and, at the same time, to achieve high transmittance, a single hole at the corner of each of the 30°, 60° and 120° bends and two corner holes of the 90° bend are modified by optimizing their diameters. This proposed optimization is almost uniform for all kinds of bending and simplest in view of fabrication compared to the previous works. Criticality of the optimized radii of the defect holes in different bending configurations have been evaluated by calculating transmittance for varying radii, contour plot of which provides selection guideline for the optimization. Simulation for the optimized 90° and 180° bends exhibit ~ 90% transmission; whereas, the same for the others show even better performances. Finally, this work also investigates the tolerances of performance of the optimized structures under the random imperfections introduced during fabrication. It is found that the optimized dimensions are less critical and the performances are robust enough for a fabrication imperfection up to 20 nm. Therefore, this work provides a unified guideline to design different types of optimized bending structure in holes-in-slab PhCW by modulating minimum number of defect hole(s) to facilitate fabrication.