John Anderson scheduled constant paced 1k reps, 600s, and 300s, as much as possible throughout the year (he called them 1500m pace but in reality they were slightly slower than that but still faster than 3k pace). You'd find that Moorcroft would be running 2:30 per km repeats in the winter and spring with 6:30 rest breaks and by early summer the reps might drop from 5 or 6 to 4 before a big race and the pace would be just 2-4 seconds faster with a 7 to 7:30 rest break. As Anderson peaked Moorcroft, he would have him do one or two really fast 1,000m or 600m or both (short and sweet workouts, so to speak), but most of the training was the same in the summer (except for a minor drop in volume frm say 90 per week to 70 the week of the peak).
One thing that must be considered as we analyze workout severity is both pace and recovery as they effect physiologic metabolism. Let's make up a hypotheticl runner to clarify the underpinnings of what actually happens. Let's say that Jo is a runner with a 4:00 recent p.b. for 1500m which is 32 seconds per 200m. In the transition from Base Aerobic Conditioning to to early competitive season racing Jo's coach may schedule some 200m intervals. If the pace for Jo is 35 seconds per rep (about 3200m pace for him, perhaps a tad slower) and his rest between reps is 200m of jogging, then the overall stress on Jo's body is moderately high but nowhere near anaerobic in nature (due to pace being moderate, the duration of the rep being short in length, and the recovery jog being reasonably long relative to the rep length...plus it was a jog instead of a standing rest which keeps the ciculatory system running effeciently at both supplying oxygen and negating potential acidic build up). Blood lactate is likely stabilize at ~ 5 to no more than 6 mmols, just above LT but not by much (equivalent to running 10k pace in extended fashion). If instead the coach cuts the recovery jog to 100m, the stress will be substantially higher, especially after about 6 reps, and the blood lactate level will go up from 5 or 6 to 7 to 9 mmols by the end of the workout. The difference is quite substantial, overall, in the effects and use of anaerobiotic metabolism.
Now, if the pace is slowed to 39 seconds per rep (82% as fast as Jo's 1500m pace), then the pace is LT but because the reps are not very long, the stress is even less, overall even with a brief 100m jogs. The blood lactate level will be about 3.5-4 mmols which is below lactate threshold; therefore it is not very stressful. The same comparison can be made for an elite 1500m runner (3:30 over 1500m) (28 seconds per 200m pace) doing reps at 34 seconds (which is something Moorcroft regularly did in training as fartlek, by the way). He could run 20 x 200m at 82% with a 100m jog and it is stricly an LT workout, which, again, isn't very hard.
An example of someone who understood this principle well and used it to his advantage was Dick Quax of New Zealand, silver medalist in the 5k in the Munich Olympics and world record holder in the 5k soon thereafter. In the base phase of training and in the transition phase he run workouts such as 20 x 400 in 70 seconds or 20 x 200 in 32 seconds with brief recovery jogs of 200m or 100m. He was simply running at LT pace. If is very common for runners to look at a workout of 20 x 400 in 70 seconds and look at it in absolute terms instead of relative terms. Dick could run 70 second per 400 for 15km straight if he wanted to.
If Dick or Jo had increased their rep speed to 1500m pace (faster than the previous example)for 200s and used short recovery jogs (100m) then it would have been a semi-difficult workout with acidosis rising throughout the workout to twice that of LT. If Dick or Jo had run 1500m paced 200s with an increased jog recovery of 200m (twice as the above example) the acidosis would be modest and in the 6mmol range, just 50% above LT, by the end of the workout.
So, back to Moorcroft and Anderson. If David had kept his 1ks at 2:30 to 2:26 but cut the rest to 2 minutes, the workout would have become quite acidic (around 10-12 mmols by the end of the workout). But, because he used 6:30 to 7:30 rests per Anderson's advice, his blood plasma lactate reached just 6-7 mmols. The rests were sufficient to get rid of the acidosis (raising ph levels close to normal values by time each rep started, which is good). If Anderson wanted to induce a quick peak (say 2-3 weeks) all he would have needed to do is cut the rest in David's workouts. The workouts would be far more intense and simulate extended hard races. Anyone who has raced a lot in a short time frame will tell you it will bring you to a peak and the crash you through the ground just as quickly.
Bowerman talked about bringing a runner to a peak quickly was simple (cut the rests between fast reps and, voila, it happens)
Think about how Arthur Lydiard peaked his runners. He built a strong aerobic base, introduced easy forms of faster work but gave them plenty of jogging recovery between reps, did some explosive stuff with hills, did some quantity "anaerobic" intervals, then got away from them. He then scheduled surge training and time trials. Time trials, Arthur said, revealed what needed to be done. In some cases, it could mean more anaerobicically natured training, but typically he would do it with more fast time trials over distances like 1500m, 800m, or 300m or surge training sessions such as 50 sprint, 50 jog, 100 sprint, 100 jog. It could mean easing off the time trials and surge training if stamina appeared to not be up to par. Thus, some long runs and easy distance runs were quickly included back in the training schedules to balance out a runner's fitness. For a runner who was low on stamina, NO extended reps which were anaerobically natured would be included, but some short quick stuff that didn't build acidosis could be included.
From my perspective Arthur was saying, "Let's get you into good shape so that 4-6 weeks before the important race we can fine-tune your training to meet your individual needs at that time. If you need anaeorbic work, I'll give it to you, but in time trial or surge training form because "I know it won't wipe you out like lots of fast 400s will. Or, I can give you 5k and 10k time trials (about 5% slower than all-out) to enhance your stamina. Or, I can give you some longer runs to give you back to aerobic endurance. I can give you some sprints with full recovery if you have good stamina and anaerobic conditioning if you lack explosive ability."
It was smart planning and adjustment that made it all work for Arthur. You can see, as a supporter of intelligent training practices, that I respect the historical influence of coaches like Arthur, Bill, and others. None of the best coaches tried to cram a bunch of hard training in the last 2-4 weeks before the peak race. They got their athletes to start the build up plenty in advance, and then they fine tuned in the last month in order to bring a runner to full form; ready to rumble when it counted most.