Page 4 of the report reads:
"Peak hours are the times when people typically use the internet; in New Zealand this is 7pm to 11pm on Monday-Friday.
Average speeds for all technologies do not decrease substantially during the peak."
This report excludes HFC cable.
Here is my SamKnows time-of-day local downstream speed graph for December ("UltraFast HFC Max").
This shows a significant peak-hours drop - although this is not obvious to a single user.
(click to view)
would you call 20% significant? seems a little over stated
how often is your connection not doing anything during those "lower" points on the graph, maybe the box is finding it hard to find a time to do the test