General features of nuclear fission can be explained using the collective or liquid drop model, but details can only be obtained by adding the shell effects. So, shell effects are moderately significant in explaining nuclear fission.

Read Shell effects on nuclear fission barriers.

see wikipedia

https://en.wikipedia.org/wiki/Fission_barrier

This combination of macroscopic liquid drop and microscopic shell effects predicts that for nuclei in the U-Pu region, a double-humped fission barrier with equal barrier heights and a deep secondary minimum will occur. For heavier nuclei, like californium, the first barrier is predicted to be much larger than the second barrier and passage over the first barrier is rate determining.

Shell effects in fission products influence the global energy balance of the fission process and play a role in explaining why fission is sometimes asymmetric, sometimes symmetric.

Shell effect is the parent nucleus largely determines the fission barrier, at least in heavy nuclei . In lighter ones, the balance between Coulomb repulsion and surface tension is the main factor; shell effects become essential when this "liquid drop" barrier is small or non-existent. The barrier is the energy threshold of fission, the amount of excitation energy that must be available to make it possible. It also largely determines the probability of spontaneous fission.

Shell effects in the fission barrier also influence the detailed dynamics of fission, like the fission path in the deformation space, i.e. the succession of shapes during fission.