I just thought I would update the thread with a few things.
One thing I will add to the excellent post by "summary" on the previous page, is I am NOT saying this is the way you must train or the only way to train. Maybe in the middle of the pages, what has got lost is the CTL and TSS talk (I think I explained it reasonably well, as quite a few people I speak to regularly are using it?). What I have always said and maintain - this being the key point; is that if you are correctly tracking your data, daily TSS and CTL , there's a good chance that you will be fitter/faster , the higher it goes, pretty much no matter HOW you get there.
My example before was when I was injured on the bike, I did the turbo trainer for an insane amount of time day after day, raised my CTL to record heights and did a power PB with a healed collarbone a few weeks later. This was purely zone 1/2 riding. But the point being with sub threshold, it's the easiest/quickest way to get a high CTL (fitness score for those not using intervals icu, same thing) being time crunched and without the extra injury risk the real hard stuff brings (as well as the relative extra recovery needed). I could get the same CTL riding sweetspot, in around half the time I did with all that easy riding and my power the next year was almost identical.
I just thought I would add that, as I think that is being lost a bit. I stick by my initial posts on paces (Hard2find I think has provided an amazing resource) but this isn't the only way to train. A big "if" but if my body could handle a Daniels schedule on more hours I'm doing now (spoiler, it likely can't) , then I would probably get faster .
FWIW , I'll put this out there, stuff I have shared with jiggy, Hard2find and shirtboy, is that since my CTL was "50" (that was as high as I could get it a more classic style) by pb at 5k has roughly gone up 8 seconds, for every extra CTL point. It's not perfectly near, but there is a clear pattern and trend.
Final note on that, I'm also working on the assumption for running, as it was on the bike it didn't really matter HOW I increased my training load, each CTL point was worth about 1.5w in FTP, up to the point I literally couldn't fit anymore into my lifestyle.
Anyway, I don't get a huge amount of time at the moment to contribute to this thread as much as I want, but hopefully some of your find that interesting and just to clear up I'm not saying this is the way you HAVE to train, but I still say based on the experience from both sports and seeing what others are doing, it's likely going to get you there in the most time efficient way.