You are replacing the brake lines and not saving the old lines to use again. Where I live in nova scotia the rust is pathetic. Flare wrenches do not cut it. We just break the line next to the caliper or whatever and drive a tight fitting six point socket on to the fitting and get a much better grip to remove them. The mechanical shock of tapping the socket on seems to ease the rust grip a little as well. Makes a flare wrench seem almost like a toy. We almost always are forced to use heat as well unless we are going into a rubber brake hose that we are reusing. The new brakeline nuts can be tightened up suficiently with normal wrenches without damaging the head. So if only doing brake work once in a blue moon flare wrenches really offer no noticeable advantage except to lighten your wallet. Now on cars less than five years old I will normally use flare wrenches to remove the fitting. . Of course if reusing the brake line I will use a combination of heat and a flare wrench to keep the line and fitting intact during removal when possible. Here the brakeline also seems to rust to the fitting as well and just wants to turn with the fitting. This must be one of the rustiest areas of north america.