I'm not sure why your link is going in a loop back to here, I do have these PDF's.
Agree, it's a piece of string.
I rarely see anyone saying the Overland Track was very easy (though expect in time they come think of it as 'easier')
This guy did:
"The 6 day suggested time is very generous, I took just over 2 days, I know some will say why rush, well because I did:-) I would get bored if it only plodded along at 10-15 km a day!
If you have NEVER been off the beaten track (i.e walking to the pub) then you could find this very taxing and adventurous but if a seasoned hill walker in Europe or the States then I think you might wonder why you have paid so much to do this"
He's obviously not the guy writing grading systems

(I wonder if he took 2 days as he would have considered one day too 'hard'

) (perhaps he is only ultralight rather than super ultralight ..)