The only thing with those plugs is they will last a
long time.. the spark jumps the path of least resistance
and that is 1 of the grounds at any one time and as
you get wear/burn it will jump to another strap but
still only 1 strap at a time.. that 3 ground strap
is a bunch of sales hype
EDIT
Its been proven that the racing plug short ground
strap makes a few more HP, opening up the flame front