So how does this apply to long days? I do long days (5 hours or more on bike, 2 or more hours running) at a slow pace while training for IM, but its not easy on the body. So even though it is slow, slow does not = easy; I need a day or two of recovery after. So how does this fit into the mix? Are those long days part of the 20 or the 80; are they hard or the easy in this context?

If they're part of the 80, isn't this what most athletes do anyway? A long day, an intensity day and maybe an additional easy or recovery day? Those long days are hardly recovery.

If these long days are part of the 20, how do you find time to also do any intensity?

Just not sure this is all that revolutionary for IM athletes (where a ton of time is already spent going slow).

This is directed at anybody, not just Andrew.