The Trail Crest Exit permit is an add-on to a normal permit, and they have attached the same date to it as the date of entry. (In years before, you needed to grab a specific exit date, which made getting one even more complex.) Now, all you need is the Exit Permit addition on your permit, and there is no official exit date assigned.
That is what I mostly figured looking at recreation.gov. Regulating Whitney exits based on entries many miles away and days before is a little weird, but I can see how the old way would get really complicated.
