My problem with this method is, if I stand close enough to get 16, I hack faster than he dehacks even if I just barely had started hacking it when he arrives... so I have to move much further back to slow it down.
Still.... it's not that much effort to go in close (get 18 for hacking and like 67 for guarding), then back away to let the percent go down, and repeat. But it does mean I can't just let it sit.
Thanks for the method, though!!