From the Autumn 2001 BMC News:
'The athletes did a morning run before breakfast, another session after breakfast and a final session after lunch. Works out at about 6miles per session. This sort of crash training, when followed by the same number of days on half training or less, resulted in major fitness increases. Dr Peter Snell found this out from his research.'
I think the key here is the rest which many people are afraid to do. I did something similar last season the weekend before I ran what was perhaps my best race of the season. I went hard on the Sat/Sun/Mon and then went easy for the rest of the week. Felt great on the Sat and will definetly do this again, perhaps for the upcoming European trials.