After years away from track racing, I did some last spring and managed to just get under 15min for 5k (14:56).
In the three months before the race I ran the following sessions.
4x1600m (5:15), 4x400m (71), 4x200m (32) 200m jog between everything.
2mi road race (9:40)
3x3200m (10:40) w/200m jog between
10k in mid 5:50s
10k road race 32:13
3x5k (5:40/mile) w/200m jog between
4x2k (6:28), 4x400m (70), 4x200m (31) 200m jog between everything
2x5k (5:19/mile) w/600m jog between + 5x200m cutdown (33-29) w/200m jog
8x600m (1:45) w/200m jog between
10x1000m (3:20) w/30 seconds 100m jog between
6x1000m (3:02) w/200m jog + 3x1600m (5:35) w/200m jog
2x4k (5:20/mile) w/200m jog + 5x200m (30) w/200m jog
3000m race (8:55)
2hrs including 2x30min @ 5:45/mile
4x1600m (5:08), 4x400m (71), 4x200m (32) w/200m jog between
5000m race (15:18)
5x150m sprint as fast as possible w/250m walk between
4x(2laps over hurdles in lane 3, 110y jog, 330 fast, 440y jog in 2:35/51) + 8laps of alternating hurdles in lane 3/flat in lane 1 in 11:30
Race steeplechase 9:44 + later in the day 10x200m in 33 with 30 seconds standstill rest between
3x(4x400m) in 67-68 w/20 seconds between efforts and 2 laps jog between sets
6x200m over 4 hurdles in 35 w/200m jog
Race steeplechase 9:35
3x(400, 800, 200) in 69, 2:18, 33 w/15 seconds between efforts and 1 lap jog between sets + 3mi in high 5:30s
4x2000m (6:28), 4x400m (72), 4x200m (33) w/200m jog between
1600m time trial (4:28) + 1 hour 5:50/mile
8x200m in 30-32 w/100m jog in 28-30 between
Race 1500m 4:05
2x(1500m, 800m, 400m) w/7-8 min walking and jogging between everything (4:17s, 2:10s, 61s)
3x3200m (10:30) w/200m jog between)
7x200m in 35-32 w/200m jog between
2400m (7:06), 600m jog, 5x200m cutdowns (34-29) w/200m jog between, 1000m jog, 1600m of fast straights, jog turns (5:00--mostly 16.x/21.x)
8x200m in 33 w/100m jog in 25-30
Race 5000m 14:56
Weekly mileages were 85, 80, 95, 56, 89, 90, 88, 74, 91, 64, 90, 66
I had a couple of sessions of short hill sprints with full recovery in there, and long runs of 12-21 miles but mostly ~15 and a few weeks with no long runs.