Figuring out the optimal taper... is an art. there isn't one specific taper that is perfect. As a jazz guitarist once told me- there are no wrong notes, only wrong ideas.
And- it really depends on how deep your fatigue hole is, how you are feeling. Generally, your last 20+ miler is 3 weeks out, and you cut back your mileage 20-30%/week. I like a 16 miler 2 weeks out, and still getting in quality fatiguing workouts up to 10 days out.
That Pfitz plan above doesn't really match the one in his "Advanced Marathoning" book- which is what I use as a guide. There is more intensity in the book than is shown above.
I start really dialing in marathon pace miles into a bunch of my runs, sometimes just 2-4 miles of it towards the end of a run. And more in the long runs. and still toss in some speed work and tempo. More Speed/tempo in your midweek runs, then less in your long run. Or- if your mid-week speed is minimal, then definitely toss in quite a few MP miles in your weekend long runs, including that last 12ish miler 1 week out.
2 or 3 days out from race day- you should still feel a little fatigued. Your shakeout run the day prior... your legs should just start feeling ready. On race morning- they'll surprise you.