Dense wavelength division multiplexing (DWDM)-based optical networks that are assumed to employ exactly two working fibers uniformly on every span are matter of recent interest in the field of telecommunication. An interesting and highly efficient strategy for protection of such networks is to use, if possible, a single dark-Fiber p-cycle formed on a Hamiltonian cycle. It has been showed that in a homogeneous Hamiltonian network, a Hamiltonian p-cycle is the most efficient overall solution, although interestingly it does not always correspond to the individually most efficient p-cycle that can be formed. The article also considers p-cycle planning in non-Hamiltonian but homogeneous networks and introduce the concept of a semi-homogenous network, specifically linked to the p-cycle concept. The proposed semi-homogeneous class of network actually realizes the theoretical lower bound on span-restorable networks in terms of network redundancy. Such networks also provide a strategy to accommodate certain patterns of capacity growth beyond a homogenous network without any increase in protection capacity. The work also demonstrates and explains why a single Hamiltonian p-cycle is not as efficient as a specifically optimized set of individual p-cycles in a "capacitated" network where the working capacity on each span varies in a general way.