I have been consistently following this method for the past 3 months. I had no races during that period, but 3 months ago I ran 2 half marathons, finishing in 1:22 and 1:23. My personal record (PR) was set 2 years ago at 1:19. After that, I focused on running 2 marathons and encountered a few injuries. Consequently, my speed in the half marathon distance dropped a bit, and I was struggling to return to a sub-1:20 half.
I slowly started implementing this training method since about September. I did lactate testing and was surprised right away by how much faster lactate accumulates than I thought, which required me to adjust my paces accordingly.
Most of my training was done on a treadmill since the weather has been poor here in the winter, and I work from 8 am to 5 pm, leaving no time for outdoor training during daylight hours. I began with 10x3-minute intervals at about 15.5 km/h, 6x5-minute intervals at 15 km/h and 10x3-minute intervals at 14.5 km/h. I successfully completed every workout and gradually increased my pace by 0.1 km/h each week. Currently, I am running at 16.4, 15.9, and 15.4 km/h. Every third week, I reduced the volume to about 70-80%, akin to a recovery week. Long run 60-90min. Now, my normal weeks consist of approximately 85 km of running, with easier weeks around 60 km. Additionally, I incorporate Zwift bike rides—easy lower zone 2 training—about 3-6 times a week, lasting 40-60 minutes, as I recover without any issues in time. On easy days when I feel fresh, I also added 6 short strides on the treadmill, lasting about 15-30 seconds, to work on a bit of top-end speed at 18 km/h with a 9% incline.
I've been using a Sole treadmill for workouts, and it seems to me that all the paces I've been running are significantly faster. For instance, the 10-minute intervals I run on the treadmill at 15.4 km/h translate to easily running sub-3:40 per km outside.
On my recovery days, I run at about 130 bpm. In November, that pace was about 5:05 to 5:15 per km, and now it's about 4:30 per km.
I've tried following many plans before with mixed results, and this approach is the easiest to follow, and I recover much faster than ever before and feel much stronger.
Anyway, it seems to me like I could run a about 1:17 half marathon right now, and I have a race coming up this Sunday. I will report on the result.