Here's something Japanese would do; they would USUALLY (man, I feel like being John Kellogg doing all these caps!)have 3~5 runs of about 40k at fairly close to marathon pace--for someone running 2:10 marathon, anywhere from 2:15~20 pace. That would be ideal. Sometimes they cannot do that often due to whatever, sometimes they may not even make it to 40k. But the race will come regardless of how well you prepare yourself so you need to accommdate. Actually this came from original idea of Lydiard. I'm not checking Run to the Top right here in front of me so I may make some mistake in detail but he had quite a lot of 15~18 mile runs at 1/2 effort for preparation for the marathon. And remember, those guys all had to work 40 hours a week in NZ. For Japanese being on a corporate team, you can afford to take good stretch of time doing pretty much nothing but training--they can stretch the distance a bit.
Lydiard's influence in Japan is actually deeper than I thought. I was just blowing the horn (well, sort of...) from what I know from the late Nakamura and coach Koide, my personal aquaintance with them and them saying how much influence Lydiard had given them. But it wasn't until I received the Lydiard special of "Journal of Running Science" published by Japan Running Academy and read articles written by some of old timers runners of Japan; some whom knowledgeable readers might recognize (like Kimihara and Shigemori both of whom won Boston) saying the Lydiard influence to Japanese marathoning as well as some younger running "statistician" and so-called "expert" talking about connection between Lydiard to Nakamura, Takahashi, Nagato...all the way to most of today's coaches--it was quite refreshing and fascinating. In fact, I'm going back to Japan next month (not because of my dad's condition, thank you very much for all those who were concerned for me and my family!) and made an appointment to meet with the president of Japan Running Academy--and he just sent me an e-mail a couple of nights ago and said he's bringing someone from Federation to talk about things like Snell's clinic in Japan... I tell ya, attitude like "Lydiard is pre-historic" is not there at all in Japan.