The enhancing effect of asymmetry in the particle capture and loss processes in a multiple-mirror system is analysed. The system considered consists of a central mirror confinement region 'plugged' at each end by N smaller-volume mirror cells. It is shown that the effective confinement time in the central cell increases exponentially with N with asymmetric cells, as contrasted with previous analyses which showed an increase linear in N for plugging cells characterized by symmetric capture and loss processes.