Six weeks apart I ran a 2:54/2:53 double. The first course was faster, but it poured rain for an hour in the middle. The second course had a few hills, but perfect weather. The only run I made a point of doing in between was a 2 hour run exactly in the middle of the six weeks. All other runs were 40 - 60 minutes easy - mostly 40'. 55 mpw is the norm for the 15 week buildup. The middle week with the 2 hour run was 50 miles. All other in between weeks were recovery/taper, about 35 mpw.
Also, a good massage 5 days after the first race and another 3 days before the second seemed to help. I didn't expect to run faster in the second, but started out relaxed, picked it up between 10 -16 and held it through 25 before it began to really hurt.
Good luck.