I recall hearing Roy Benson cite a study where 3 a days were documented to be more effective than 2 a days and even more effective than singles. The particulars were something to the effect of 3 runs of 3 miles over 12 hours, 2 runs of 6 over 12 hours or 1 run of 9 miles every 24. The research was early 70's, but I never found anything solid. Aside from anecdotal evidence--such as the Kenyans do triples, so it must work--have you seen anything like this? Are there any substantial claims to this type of approach?