How to set the time integration parameter when there are multiple viscoelastic layers with different Maxwell time

[ranneylxr]

Hi all, In the guidebook, the integration time seems to be equal to year/tm, where year is what user wants. My question is: when there are multiple viscoelastic layers with different Maxwell time, which tm should be used to calculate the integration time? For example, there is a jelly sandwich model where the tm of the lower curst is tm=10yr and the tm of the asthenosphere is tm=5yr. Then I want to calculate the post-seismic deformation after 70yr, how do I calculate the integration time? Should it be 70/5 or 70/10? I am confused by this for a long time. Thank you very much!