Zoom,
I ran my 68 off of really not that much long training. Did alot of miles from 80-100 which varied! I'm your type of Long Distance runner, who has speed, but not 4:00 mile speed. My key workouts were 7.5-8 mile tempos, 5 x 1mi, 5x 1.5miles, 4-5 x 2miles. Nothing to special.
Now i look back and i wish i had did more of a longer run instead of just 13-15miles! more like 16-18.
Right now i am training for my first marathon in october, and i plan on racing a half in september as a tune up! I plan to do some half marathon interval aka(3-5x 2mi 6 x 1mi, 8-10x 800...etcc) I also plan on doing every other week 16-20 x 400m, the other being 10x400m Hill repeats.
While keeping my mileage around 100-115. My goal is 2:25.
So i hope my info will assist you in your path to a Sub 66.
Good Luck and Remeber, Consistancy is where the true training game is, not who can trash threw workouts!
Goodluck.