This paper deals with the strength of panels composed of three and five plates connected transversely and loaded along the longitudinal direction. First, a comparison between the strength of panels having asymmetric imperfections and of single plates is made, which allows evaluating the ability of the single plate to properly simulate the panel strength. Following this, the results obtained for a panel model having symmetric imperfections are confronted with the results of the asymmetric imperfections. The asymmetrical and symmetrical models of the panel give respectively the lowest and highest strengths possible (imperfections in adjacent plates with different amplitudes have “in between” strengths) allowing to establish limits to the variation of the strength. The results show that using a single plate can be conservative or nonconservative, depending of the plate slenderness and shape of initial deflections. It is concluded that for design purposes it will in general be enough to consider assemblies of three plates, as the results for five plate assemblies are not much different.