RE: Best method of cardio
you are refering to HIIT i presume, if so your understanding of it is wrong. it is not rest, you just lower the intensity to about 40-50% of your MHR. the first one you mentioned is not correct at all.
it would be more like this:
and that goes for any activity, boxing/running/cycling/rowing etc etc
read my article [sticky at top of this forum] and scroll down to HIIT, there is an example routine there.