Vindicating the Pauling-bond-order concept

In the Pauling-bond-order concept, it is assumed that all Kekulé structures of a benzenoid molecule contribute equally to the π-electron contents of the carbon–carbon bonds. We modified the Pauling-bond-order: (a) by increasing the weight of a Kekulé structure proportional to the number of Fries-type hexagons and (b) by increasing the weights of the Kekulé structures that are compatible with Clar aromatic sextet formulas. Improvements in reproducing experimental carbon–carbon bond lengths are insignificant, implying that equal weighting of Kekulé structures is more justified than one could anticipate.