First realize that "corner" models are a pretty weak cartoon,
of true process / device variability. These corners serve to
support timing / drive strength models and little else. They
are wholly inadequate to analog interests and embed
assumptions about correlation of detail params (for
example VTN and VTP, u0n and u0p are co-variant in these
models when in fact there's no such process correlation
(toxn and toxp, there's only one tox for a given voltage
rating family of FETs).
Since it's all a cartoon I don't know what you'd try to figure
out from it - or whether you'd be smart to believe it.