Ok, I'll bite...
In 2009 or 2010 I rode from Phoenix to Tucson to El Paso to Dallas to Madison. I made pretty good time from Dallas to Madison: 13.5 hours.
I've ridden from Madison to LA in a little over 48 hours, and from Madison to Seattle in just under 48 hours.
I've driven a car from Madison to New York in 17 hours. This I've done several times.
After the ride from Dallas to Madison, I got into my truck and drove to Minneapolis.
Three days from Phoenix to Philly will be tiring, but otherwise easy.
You'll have to stick to interstate highways and you'll want to go about 7-9 mph over the speed limit.
Go to the IBA website for info. Especially on lights, diet, hydration, fuel, road hazards, basic bike prep, basic bike maintenance, and all kinds of shit you need to know.
I used to like this kind of thing. Somewhere between St. Louis and Madison, after riding close to 100 mph all the way from Dallas, I stopped liking it at much.
I would offer a little bit of a different opinion on the practicing. I would say, Don't Practice. Because ignorance is bliss. The first time I rode 1000 miles, I actually rode closer to 1500, and by the end, I'd ridden from Tampico, Mexico, to Madison, WI in about 72 hours.