Start with an honest evaluation of your overall fitness. The question isn’t so much: can you walk ten or twelve or fifteen miles a day. The question is: can you walk ten or twelve or fifteen miles a day, FOR FIFTEEN OR TWENTY DAYS IN A ROW? Many can answer the first question, “Yes.” Few can answer the second question that way.
This is particularly true if you are in your forties, fifties, sixties or beyond. Three days of unusually demanding exertion, followed by thirty-six hours of recuperation, can first stress your body and then allow it to repair and recover in a way that leaves you stronger. Follow that with a period of five to eight days of similar exertions, punctuated with another rest day, and you’ll find yourself ready to push through to the end of the trail.
Alternatively, without time off your feet, you may find yourself getting progressively more beat up, setting yourself up for injury (or disappointment, when you find you just don’t have the capability to continue).
On the other hand, if you are young enough to recover overnight (oh yes, I remember those days!), or if you are already accustomed to this sort of relentless effort, without rest, zero days serve no purpose, other than to allow you to loiter in a particular area for a while. (Loitering in a particular area can be a VERY good reason.)
My advice: unless you are sure you can do this hike without taking a day off, schedule at least two.
If you are hiking southbound, there are four places where you can take zero days during the first half of the trip—and pamper yourself a bit in the process.
They all have accommodations and they all feed you, one way or another. They all have advantages and disadvantages.
More, in the next two weeks, regarding each of these locations.
Good hiking, Ray