Two quotes from Noakes:
"In chapter 2, I discuss recent studies that cutting out much of this slow training, but retaining the speed training, does not impair performance, at least over shorter distances of 5 to 10km".
"Since the 1950s, there have been at least 92 studies of this topic [altitude training]. Of these studies, 76 are scientifically unintelligible because they were conducted without an adequate control group..."
Discuss :-)