Numerical integreaion and change in clearance over time

Hello NONMEM Users, When clearance changes over time, the classic analytical solution for the 2-compartment linear model is not correct. Nevertheless, if the change is only ~30%, one can say it is still acceptable. Time required to run an analytical and numerical models is drastically different, which can be important for decision making. Did someone had an experience submitting using analytical solution when clearance changes over time to an agency or a journal? Can it be acceptable? Thanks, Paul