This. Definitely this.
There is a certain chasm between what we mythologize what Lydiard did versus what he actually did.
I had to go find my old notes and books on Lydiard. In Chapter 12 of "Running to the Top", he sets out the training schedules. For the various track events, he has the conditioning phase of daily aerobic runs, like 30 to 60 minutes or 60 to 90 minutes. However, he describes aerobic runs as 70% to 99% of your aerobic capacity.
Well, 70% to 99% of your aerobic capacity sounds like something between easy running up to 3k or 5k pace running. That's some pretty hard running. So it would probably be a training error to think that Lydiard training did not touch on faster paces during the conditioning or base phase.
I would also add that he has a different conditioning phase for xc and road racing. In a two-week cycle, he has aerobic running, running a hilly course, a time trial of 2k to 3k, and another time trial of 3k to 5k, Again, that is a lot of hard running in the "base" phase.
Similarly, in "Running With Lydiard" for the conditioning phase of men's training for distance track events, the schedule is:
Monday: Easy Fartlek one hour
Tuesday: Aerobic run of 1.5 hours
Wednesday: Time Trial of 10k
Thursday: Aerobic run of 1.5 hours
Friday: Easy Fartlek one hour
Saturday: Time Trial of 10k
Friday: Aerobic run of 2 hours or more.
Again, that is a lot of hard running. While there was periodization to Lydiard's training, it would be a mistake to think that certain speeds and paces were left out of training until you reached a later phase.