Thought I'd add my anecdotal experience to this.
M28. Came into this after 3 Pfitzinger builds to marathons. Two resulted in tendonitis (knee and then hamstring) so both were DNS. Other build resulted in a 3:03:15.
Was a bit fed up of putting in the effort and getting injured when I felt like I was running so well and getting in good shape. I also fell into the trap of chasing mileage, needless doubles and running the Pfitz recovery days too fast. 10k PB from 1 year before I started this of 37:57. I REALLY had to have a rest day every week and invest time in S+C (I haven't done any since June now).
Since May have been doing the following structure to total 8 hours/week:
M: 60' E
T: 10x4' off 60s
W: 60' E
T: 3x12' off 60s
F: 90' E
S: 30' E
S: 6x7' off 60s (90' E here if I do a hard Parkrun on Sat)
First parkrun to set the paces was 18:29. Have slowly chipped away at this.
Bar 5 days off with bad Manflu, I've never felt the need for a rest day and have enjoyed the monotony. Had a 10K race in August, which just felt horrific and felt like I didn't have any sense of the power I used to. Ran something like 38:30, and thought that was the end of trying this. Put it down to a bad day, told myself I'd give it until my half in October.
Kept going with it, and 2 weeks ago I got a Parkrun PB in 17:49.
Going into a half today, I was doubtful of the system as I basically had no idea what running the distance would feel like or whether I could hold on. Mentally felt like I needed that traditional long run.
Conditions in the UK have been pretty perfect for running today so that plays into it, but I just felt.... strong? I never was gasping for air despite everyone around me doing so, I could just keep squeezing the pace and just naturally found my rhythm.
Ran 1:22. The only time I started to feel like it was getting tricky was in the final 2km where I actively tried to push for the line.
Glad I stuck with this and gave it a good shot. I don't doubt some that say I could get to the times training in other ways, but this is the first time in 2 years I've managed to stick a long term block together without a flare up and going to stick with it now. Excited to see how I do in the marathon come April next year.