excellent article not again.
I must admit i'm a Lydiard fan and since Snell was one of Lydiard's finest students i'm hoping to meet him one day.
I think what Dr Snell is saying is more along the lines of pay serious attention to the skill of running. Become as efficient as possible in that way as well as in your physiology.
This 6 weeks adaption timeframe i have found is correct. Work continuously and intensely on an attribute in a particular way and adaption rapidly slows after 6 weeks. So change the stimulus and it can continue.
In terms of the training Dr Snell actually did. I believe it involved of doing marathon style training for most of the year followed by a period of specific latate tolerance work and explosive hill bounding. Following this is the sharpening phase which basically allowed the full running speed to be expressed through low volume/high intensity training and race pace rhtyhm training. 6 weeks for each phase with the sharpening phase ending in the major race. IN Snell's case it was a couple of Olympic Games.
I thought i should add that after finishing coaching in New Zealand Arthur Lydiard was invited to different countries around the world. He spent two years in Finalnd in the late 1960's and worked closely with a few coaches. Two of them coached Viren and Vasala.
Lydiard believed that the hour steady run should be a standard and able to be done daily without any negative training effects.