For a while now, whenever I have to cut into an existing wall above the ceiling in order to feed a new added device, I have cut a work hole into the sheetrock by cutting in at an angle pointed to the inside of the hole on only three sides. I then open up the hole and leave the hole middle piece hanging by the flap of the fourth side. This way I can feed the flex down the wall and then cut a notch so that I can put the flap back into place and the angle of the edge allows it to fit back in without falling in. Then I take tape and mud and patch the cut line and finish off by fire caulking around the flex. I have never been turned down for this but I have often wondered if this would not be an approved method. Do you think this is ok or would you as an inspector require a blow out patch?