I think a couple shorter / harder races are good workouts (instead of a tempo or interval workout) within the training cycle.  Race pace for the half or full are pretty gawd-aweful workouts for me.  For the full, I like to do 1 mi w/u, 10 mi at race pace (effort) for each of the last 3 weeks up to race week.  Last one is about 10 days out (per Hansons plan).  These can be very difficult and uncomfortable runs, but it helps fine-tune race pace.  And if you get the taper right, then race pace is comfortable on race day.  It's kinda weird.  With about 10K to go, you just suck it up and deal.

 

FWIW, the Hansons' repeated hammering of MP runs did help my ability to lock in that pace pretty consistently. But it did not help me hold on to it for the last 10k of the race; faded hard every time. Of course there are always many factors, so I'm not blaming the Hanson bros for my failures. But I don't think most other plans emphasize MP runs nearly as much. More commonly I've seen it only as part of a fast finish LR, a few times in the cycle. Such as Mr. Pfitz and his famous 18 miles w/14 MP. Which is a joy.