He mentions that as it is a fairly common TRT dose and the author is advocating only supplementing enough test to replace that which is being suppressed. For me, that would put me at <300ng/dL (low T), so it obviously does not apply to everyone. I did find it to be a pretty informative read though. I'm of the opinion that you should find out what works best for you and run with it as there are a zillion different opinions on this topic.
My .02c