In the principle of the Lydiard method, you will develop different aspect of running; i.e.; aerobic, anaerobic, pure speed, etc.; separately and only blend them together when it's necessary at the right moment. What you do today is not necessarily the reflection of what you CAN do; but rather what affects your actual performace tomorrow. I'm sure some of you might argue the scientific validity of some of Lydiard's comments such as "it only takes 4 to 5 weeks to develop your anaerobic capacity to maximum"; I don't even know if there has been legitimate scientific study done on such subject and I can't answer that though, as far as I'm concerned, his coaching runners based on this principle hurt none of them perform the way they did.
What I have a hard time accepting when people say that you have to train the way you race (speed, anaerobic, etc) is that it, sounds to me, is based on the principle that "racing every week, it not every day, is the best way to train for racing." What's better than running 800m in 1:44 than running 800m in 1:44 everyday (or every week or whatever) because you are doing exactly what you want to do for the race!? Well, good luck! You don't try to run the marathon distance every week to prepare for the marathon, do you (well, some people do!)?
Do you really need to work on the speed you're expected to run in the actual race year-round? Does that mean a marathon runner would not need to run faster than the marathon race speed? Would 800m be the longest you need to run to prepare for 800m race? Okay, I'm exaggerating; but isn't this the principle that some people base their training "theory" on? In the Lydiard method, you look at different parts of physiological and mechanical aspects of "performance" separately and develop them separately; and blend them all together in a timely fashion so you can peak on the day(s) that you want to perform at your best. You may lose a race or two in March (some people argue you need to have the race speed year-round); but you will be at your top speed in July when you want to be at your top speed.