In this article, Power Transfer Distribution Factors (PTDF) and the underlying flow-based model proposed for capacity determination and allocation in electricity grids are studied. Several factors with influence on PTDF coefficients, such as topological and seasonal changes as well as zone-building, are empirically analyzed using an AC power flow simulation of the UCTE transmission network. Furthermore, the determination of border capacities is examined. According to the findings of this work, introducing the PTDF system in the highly meshed UCTE transmission system seems only feasible with a nodal network model, as the scattering of the coefficients due to the aforementioned factors precludes an efficient use in a zonal model. Moreover, it is shown that border capacities are overdetermined in a zonal model and hence cannot be computed univocally.