run 1) Canova, Hudson, and Hansons have their runners do intervals at slightly faster than MP. 6 x 1 mi at MP-10s (and other variations of 6 miles at MP like 3 X 2 mi and 2 X 3 mi) seems to be the bread and butter. High mileage guys seem to like 3 to 5 x 3 mi.
run 2) The Hansons advocate the continuous MP run (6-10 miles) be separate from the long run but it seems Hudson and Canova (and lots of other marathon coaches) combine the two, so a 20 miler might be 10 at MP - 1 minute and the final 10 at MP.
Regardless, a commonality of Canova, Hudson, and Hansons is putting in about 25% of the weekly volume at MP. Since I began my sharpening (MP) phase, I've been right on 25% although I was a little low the week of the pemi loop (because of an absurdly long, long run) and really low last week although I did get in 12 miles (the Bruiser) at about HMP.