This depends on the quality of the foundry PDK models.
A "digital" flow must be suspect, as this region is not in
the mainstream of applications and would only affect
SPICE simulations of leakage in the context of a digital
library based design.
You would expect an analog / mixed signal kit to pay more
/ better attention to this.
ID "too small" for W/L might mean simply that other things
(noise, matching, voltage drop) matter more than model
accuracy, or accuracy was judged OK.
At any rate if you care about physical outcomes then some
effort to validate model accuracy and coverage of process
variation, is warranted. You may or may not find modeling
docs from the foundry (laying about, or by request) that
speak to the care taken and results achieved.