I seem to have a pretty unusual runner's physiology in being an absolute plodder, born without a single fast-twitch muscle fiber in my body. I struggled desperately to run an 80-second quarter and my best time for the mile was about 5:40. A 4:30 1500m is otherworldly to me. But what I could do was grind out close to a maximum effort for a very long time. I ran three marathons under 2:48, including my OTQ of 2:42:50 (on an honest course, Twin Cities) but I never broke 18 minutes for 5K. So what worked for me might not work for a more "normal" runner.
This was a long time ago and I don't have training logs from back then, but more or less this is how it went. I was a casual runner through my 20s. I am 5'5" with a small bone structure and very narrow through the shoulders and hips, and in my late 20s I weighed around 130, way overweight for a runner. About age 30 I got serious about running, cleaned up my diet, gradually ramped up from 20-30 mpw to 50+ over the course of a year or so, and slimmed down (over a couple of years) to about 105. I looked like a concentration camp survivor but I did get faster.
During the 12-month period in which I sliced my marathon from 3:08 to 2:43, I was running roughly 75-85 mpw. Typically this was a steady 8-10 mile run each morning, one mid-day interval workout per week (quarter intervals or mile repeats), and one weekend long run. Long runs were usually at least 16 miles and went up to about 24. I never ran quite the marathon distance in training but I sometimes ran for as much time as the marathon would be. And the long runs were often done with a group that included some good male runners, and they were hard efforts, not just jogging along for 20+ miles.
Somehow, despite all that volume, I managed not to have a significant injury until the day of my OTQ race. I finished the race OK, running the last few miles with a sense of elation that I had a big time cushion (the standard was 2:45) and I was still running well. However, several hours after the race I could barely walk or use my ankle enough to drive a car. I got over that injury but after that it was one injury after another, until I gave up on trying to run fast.
I am now two weeks short of age 59 and still running regularly, but I can't seem to stay uninjured long enough to train for a marathon. I run lots of half-marathons but am now doing well to get in under 1:45. Which is still very competitive in my age group in local races. And I still do a lot of volume, 70 mpw on a good week, but almost all of it slowly. I still love running and hope to be able to keep doing it for a long time.