I have done this program. I say you MUST do a 6 week or so hypertrophy phase prior to it.
I set up my summer program like this: 4 weeks 4x10, 4 weeks 4x6, 4 weeks of 3x5 3x3 5-3-1… This is like the volume/intensity X shaped graph.
In my findings, 5-3-1 converts the strength you developed from previous weeks into maximal strength.
A coach of mine told me a cool story. It didn’t directly relate to strength or anything but it went like this: A bamboo tree takes 6 months to grow to a full height of 100 feet. In the first 5 months it grows a mere 10 feet. Then in the next 30 days it grows an astonsihing 90 feet. He said, do you think the tree was able to grow that last 90 feet because of something that happened in those 30 days or was in more in part to to the 150 days of root strength, and nourishment?
Hopefully you can see the connection. Hard work in the offseason so to speak is only revealed when the intensity increases. This is also partially taken from the CFTS