There is no reason for NOT running, sometime, longer than the distance of the Marathon. Bordin wanted to run about 50-52 km in altitude before his top events, also when, for Luciano Gigliotti and myself, this training could be already useless. When we asked him why he wanted running 3 hours (52 km), he answered "because after this I feel more mentally comfortable and my self confidence can grow".
Also Shami, for example, during periods dedicated to the gym (during October, November and half December he went to gym 9 times per week, with 4 days with sessions in the morning and in the afternoon), had ALWAYS one weekly long run of 45 km, increased till 50 km, at moderate speed (about 3:40 p/km with last 30:00 faster).
However, personally I think that Japaneses exceed in long continuous runs, epecially when are already more old, and had already some physical problem.
In the training of Toshihiko Seko, that was the greatest Marathon runner from Japan, there was a training of 100 km, that they called "mentalization". It seems that Seko, and the top runners of his era (Itoh, the twins Soh and, some year later, Kodama) had a "special week" of volume of about 480 km (300 miles), normally 3-5 weeks before the race. For the ladies, the max distance was 70 km, and Takahashi used to do it several times during the period 1998 - 2000.
Personaly, in Sankt Moritz, I saw Noguchi running 3 times per day ALWAYS in 2004, and ALWAYS running, also for going to a shop for buying something !
A good example about this attitude is Eriko Asai, athlete that tried to qualify for OG or WCh, now I don't remember exactly, but failed the goal because was defeated in Osaka marathon in the final sprint, with 3 or 4 athletes together in aomething more than 2:26. About one month later, if I well remember, she ran the only competition in her career of 100km, MOVING THE WORLD RECORD FROM 7:12 to 6:33, that gave her the 7th position all time, men included. Of course, it's possible to do such a performance ONLY IF LONG RUN OF 70 km OR MORE ARE NORMAL PART OF YOUR TRAINING.
This may be a reason because Japanese marathon runners are not able to last long time. The best women are very young, and disapper in 2-3 years, because they go to destroy themselves under mechanical point of view.
A simple question : for an athlete able running 42 km at 3:18 pace, like Takahashi, which physiological effect can have to run 40 or 50 km at 4:10 ? On the other side, she uses about 50,000 steps for that training, and, if there is some problem in her body structure (she had a lot of injuries during the last 6 years), you go to increase it.
So, my opinion for when you are old of career, is to reduce the general mileage in order to preserve the body structure, but to increase the quantity of "specific mileage", for giving new stimula to the body. For example, if you were able to run 4 times 5 km at 102% OF YOUR MARATHON PACE with 1 km recovery at 95% of MP, after 10 years of career you must go for 5 times, or 5 times plus a final 3k at max speed. If before your long run was 30 - 32 - 34 - 36 km progressive starting from 92/94% of MP for finishing at 100%, now you can alternate 35 - 38 - 40 km at even pace of 98%, or, during a long run of 40 km at 85/90% of your MP, you can put 4-5 times 2 km at your HM pace, for increasing your ability in recycling a higher percentage of the glycogen you used, changing your engine from normal diesel in turbodiesel.
That's the reason because I don't believe too much in a real come back to top level of Takahashi, next Sunday in Nagoya. On the other side, if she is able to qualify. I'm personally very happy for her, because, with her passion, caparbiety and aggressivity, is an example for all the world, and when an athlete works so hard we have always to wish all the best.