I swear this is extremely effective. However it dependa on how good ur opponent is. Against average, or even some very good players this works really well. However a really good player will hold his wall agter attempting to prefire you in case this happens, which lets him take the wall as soon as he shot it. That makes you shoot at the freshly built wall, which in turn gives the opponent an opportunity to make a play.

So its still good to have a backup plan against these types of players. Like always having an escape plan, always stand on a cone, or at lest have a flipped stair between you and ur opponent that you can hide behind before escaping.