Here is a summary of my best times using different training systems.
Before (age 20-25)
Running 50-60 mpw for track in college (lots of intense intervals), 70-90 mpw for cross country and up to 110 in the off season. Post college 70s to 80s mpw for road racing, mostly single sessions (usually just one interval session a week, sometime a second fartlek or some hill work)
800 m – 2:05.4
1500 m/mile – 4:17/4:31
3K – 9:03
5K – 15:28
8K – 25:45
10K – 31:45
15K – 50:35
1/2 marathon – 1:11:05
After changing training (age 26-35)
Training as described in previous post (45-55 miles a week, periodized with two or three quality days a week)
800 – 2:03.9
1500/mile – 4:05/4:26
3K – 8:54
5K – 25:35
10K – 32:11
15K – 49:41
Half Marathon – 1:13:18
Post script
The training system I used worked very well for 8 or 9 years. I only had two injuries in that time, each taking about six weeks to heal. One was from doing a set of 200s (like 6X) too soon after XC ski season, followed by a road race a few days later, and I ended up with Achilles tendinitis. Second time was an ill-fated attempt at the steeplechase at age 32, 10 years after not racing the event post-college. I did PR by 10 seconds, but ended up with plantar fasciitis from landing in the water pit.
However, from age 35-39 things really fell apart and I could not keep up with the training intensity for long without getting injured. I was injured at least half the time those years and couldn’t even put together a decent training block.
If I could do it all again, I would have done a couple marathon/half marathon cycles in my late 20s or early 30s. I was just concerned of getting injured. Other than that regret, I enjoyed the moderated training and feel that I got the most out if it I could.