LDPC codes are deployed in many modern wired and wireless communication systems. While fully-parallel LDPC decoders are very efficient, they typically suffer from routing complexity. The Split-Row method effectively reduces this complexity with a minor performance loss. This paper shows the importance of symmetry in Split-Row architectures and proves that the implementation of Split-Row decoders based on new proposed smart column-permuted versions of parity check matrices leads to a better error performance as well as a more efficient hardware. Moreover, in order to achieve optimized column-permuted parity check matrices, a heuristic approach is proposed. This method is then generalized to support QC-LDPC codes. Applied to IEEE 802.3an (10GBASE-T Ethernet) and IEEE 802.11n (Wi-Fi) LDPC decoders, the new technique improves the error performance, while leading to almost 3x speed-up in the synthesis compile time and about 10% reduction in the critical path.