Fission excitation functions of compound nuclei in a mass region where shell effects are expected to be very strong are shown to scale exactly according to the transition state prediction once these shell effects are accounted for. The fact that no deviations from the transition state method have been observed within the experimentally investigated exci-tation energy regime allows one to assign an upper limit for the transient time of 10 −20 seconds. PACS number(s): 25.85.Ge, 24.75.+i