Or another test: after the 'sit' part, how far do you go before the croll starts to slide up the rope? All of that effort is wasted.
Or how much effort can you put into a complete frogging cycle without actually going anywhere (but just starting to move each ascender)?
The human body is designed to move weight from foot to foot but not from foot/feet to a strap that goes round your waist. Even if you assume no slumping backwards, there will still be a bit of slumping downwards.
I just need to work off the winter chocolate and get my fitness up enough that I can actually manage ropewalking for more than about 10m!