I guess I'll chip in here to provide another perspective. This is the last 8 weeks of my 5th year fall season in college (fall of 2014). I didn't have cross country eligibility, but I still raced most of the season unattached and finished my season with a 1600m time trial and then a 5000m time trial. I ran 14:53 in the 5k, but I was paced through 1k and then led the rest of the way, so I'm pretty confident that I was capable of barely under 14:50 that day in the right race. I'll just go through the weeks with weekly mileage, any workouts, and long runs. This will be a lot to look at, but I wanted to go back and look at that training anyways, so hopefully this helps somebody in some way. For what it's worth, I've also got very little speed (58 400m best)
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Week 1 - 101 miles
8 x 1 mile (grass and hilly) with 2:00 jog rest, 5:26 average
2 x (4:00 on, 3:00 on, 2:00 on), 1 x (3:00 on, 2:00 on) with 2:00 jogging between each (5:46 overall average, grass and hilly)
18 mile long run in 2:00:00 (last 3 miles at 6:00)
Week 2 - 90 miles
7 x 1200m (grass) with 3:30 rest and 400m jog, 3:44 average
12 x 600m (track) with 2:30 rest and 200m jog, 1:47 average, last rep 1:39
2 x 4k on Roy Griak cross country course (hilly) with 5:00 rest, 5:27 average
13 mile long run, 6:55 average
Week 3 - 82 miles in 6 days
6 x 5:00 on (Starts at 3:00 rest and decreases 0:30 each set to 1:00 rest), average 6:00 overall (grass and hilly)
Long hill workout (6600m of uphill), reps between 300m-800m, anywhere from 5:00-5:20 pace uphill
14 mile long run, 7:17 average
Week 4 - 87 miles
2x800m 2.5'r, 1x1200m 3.5'r, 2x1600m 5'r, 1x1200m 3.5'r, 2x800m 2.5'r (all on grass), everything between 4:50-5:02 pace
4x(3x400m, 0:30 rest) 3:00 rest, 70 average (track)
20:00 tempo (5:25 mile), 5:00 easy, 15:00 hard (5:05/mile), all on road
2x800m 2'r, 2x1200m 3'r, 2x1600m 4'r (all on track), pretty much all at 4:48 pace
No long run
Week 5 - 89 miles
8k cross country race in 25:25 (heavy rain postponed the race from the previous weekend, flat but sloppy course)
6 x 2k with 2:30 rest, on grass and hilly, 6:43 average (5:22/mile)
15 mile long run, 6:31 average
10 miler followed by 4 x 200m with 1:00 rest, all in 31.x
Week 6 - 81 miles
5 x broken 1600 (grass) with 4:00 rest and 400m jog (broken into 1k, 200 brisk, 400), average 3:06, 44, 73
10 x 600m (track) with 2:30 rest and 200m jog, 1:45 average
8k race in 25:27 (flat course but hot)
No long run
Week 7 - 75 miles
4:00, 5:00, 6:00, 6:00, 5:00, 4:00 on, 2:00 easy between each (grass and hilly), covered 7.5 miles at 5:44 average
1600m time trial in 4:23.2 followed by 3 mile controlled tempo at 5:37 average
No long run
Week 8 - 45 miles
1 x1600 4.5'r, 2x1200m 3.5'r, 3x800m 2.5'r (all on grass), all between 4:50-5:00 pace
5k time trial on track in 14:53 (previous PR was 15:13 from March 2013)
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So this was in the fall on 2014, and that 5k is still unfortunately my PR today. There are lots of things that I'd do differently looking back at that training, but obviously something worked about it since I still haven't beat that time. Here are some things that I think are key from that fall.
-Really consistent day-to-day and week-to-week training, 8 straight weeks of 80+ miles, peak of 101, only 2 days off in 11 weeks before the 5k
-Lots of workouts on grass, and most of that grass interval work was right at or under 5:00 pace
-Most of the mileage was at 6:30-7:00 pace, very occasionally slower or faster
-Lots of desire and motivation