Is the additional complexity inherent in these configuration spaces physically meaningful or, indeed, observable? An initial consideration towards answering this concerns energy scales. For the chemical examples given here, the potential energies associated with much of the configuration space are extraordinarily high. As such, these regions are essentially inaccessible for compounds at thermal equilibrium. What remains, however, is a connected network of potential energy wells separated by more modest barriers. This is expected to be a general feature of most polytopal rearrangement configuration spaces for ABn systems. While for AB4 the barriers are somewhat high for most combinations of elements, for AB5 the analogous configuration space (the AB5 TBPY-5 E′-mode) contains pathways corresponding to the Berry pseudorotation mechanism (Fig. ) that is renowned for exhibiting extraordinarily low barriers between the potential energy wells. Consequently, consideration of comprehensively generated configuration spaces must be examined and the limited focus on energetically isolated subregions only employed when specific chemical implementations or a narrow focus warrant it.