"When everyone else is running first, you'll be running last, but you'll run first when it's important" (Arthur Lydiard)
Not only is the above quote anathema to the overarching mentality of instant gratification and the "quick buck" that pervades society at large today (possibly stemming from American culture), it speaks to athletes who have complete control of their ego and who possess immense patience and self-discipline.
No man epitomised this mindset more than Lasse Viren who would spend years on his endurance phase in between Olympics. As Keith Livingstone puts it in his book "Healthy Intelligent Training": "Viren was prepared to run several extra thousand kilometres in training at controlled aerobic speeds in Finnish winters and forgo gold at competitions as important as the European Championship in order to win the ultimate prize..."
Yet, the quote above, as Keith also points out in his book, is a caricature: A well-rounded athlete won't be last, of course; he'll race solidly all the time but only when its important will they run very well.
So how many runners have looked at their fellow runners and thought "another excuse" when hearing tales of heavy aerobic miles, "not ready to peak yet", and "I'd be worried if I was running well now". A few I would gather, and undoubtedly there are some for which these phrases are just mere excuses.
But not for the patient, calculated runner who is, like Luke in Star Wars 4, "always looking at the horizon". There are no quick-fixes in running, there are no magic bullets. Forget about magical "5-week programmes" or "6 weeks to a marathon" or "how to beat your 5K every time".
Anaerobic training is as Lydiard said "eyegloss": Year-on-year consistent, uninterrupted, and progressive improvement only comes through endless hours spend stimulating your aerobic base and then polishing it off shortly before competition. This process must be repeated tiredlessly, year after year, season after season, decade after decade.
The wrong type of training such as employing circuit training (scientifically proven to boost your VO2 max) can indeed create a quick surge in performance but with too regular or random application of such methods your will see your running form oscillate throughout a season and over the years. Improvement will be marginal and random, injuries will be frequent, whether you have a good race or not on the day will be a flip of a coin.
Take the circuit training programme: This is basically anaerobic training (and quite intense at that). It will polish of your anaerobic capacity and as a result you will run better in the short term. But it comes with all the pitfalls of anaerobic training: You must continue it once started or lose your peak, it eats into your aerobic capacity, its stresses your endocrine system, it increases risk of overtraining and injury and its a suboptimal strength builder as your muscles will often be shut down by the brain well before the best strength stimulation is reached.
Yes, it increases your VO2 max. My comment on that: "Big Deal!" As Noakes suggests in his book "Lore of Running", there is no clear correlation between performance and VO2 max and here is why: Good runners have a high VO2 max because they can run fast and thus need a lot of oxygen, they don't run fast because they have a high VO2 max. Energy-efficient runners in fact often have lower VO2 max yet perform better than less efficient athletes with higher VO2 max.
So stay away from the quick-fixes, no matter how glossed up they appear on the pages of running magazines.
The Personal View
This is how I look at the world of running: My performances in this cross-country season are solid but unspectacular in the extreme. This is exactly as it should be. I could start doing race-pace reps, 30/30 VO2 max sessions or similar and within 1-2 weeks my cross-country performances would improve.
But the price would be high: Disturbance of my aerobic training, higher injury risk for the new season, and many more factors that all will lead to damage the long-term goal. For all the mistakes I have made as a runner I have never had a bad day on a race-day that really mattered to me, that was a stated priority target.
As Lydiard said, until you know what makes you race well on the day and can replicate it, you don't know anything about trainng, you're just a runner who will one day run a good race. I believe that every time you give in to a short-term goal and compromise your overall training plan to do so, you move further away from your overarching objective: The End-Goal.
Aged 30, I don't feel I have the luxury of delaying the day when my full aerobic potential has been realised, when I have developed my strength and power to its maximum and polished off my anaerobic capacity fully. That peak will almost certainly be almost 5-7 years away and it will not last very long (a few years at best). But its not like hedging all bets on the flip of one coin: While anaerobic training can fail and is unpredictable for each individual, the years of aerobic training works the same for all.
I'll end with a final quote from the master: "It's a lot of hard work for five, six or seven years. There's no secret formula. There's no short-cut to the top."