In my lifetime --I'm old-- I've been privy to three near really bad failures of brake systems concerning a "single" master.
My second car, one of my 57 Chevies, cracked a tube, from rust? vibration?, and started a leak. Fortunately, I was in an area of little traffic, and managed to get it stopped and towed it home. If this had happened "downtown" "charging" towards a stop sign with traffic backed up.........
My old Landcruiser, a 62 "blew" a cup out of a wheel cylinder. This was not pretty. The solid lifter 340 saw many many grand, as I furiously double-clutched it from about 3rd to first and dumped the clutch.
A friend of mine had bought a Ford Ranchero. Our road, a long straight stretch known as the "Baldy Road" intersects "Boyer" at a T. Fortunately for my friend, directly across from this T intersection is a darn poor power line inspection road. He had just bought the car, and some idiot had damaged the brake line to the rear, and had spliced it back together --with RUBBER HOSE and FUEL HOSE CLAMPS!!!! (Remember C.W. McCall? "Sorta like steppin on a plumb")
Anyhow, he was chargin' down Baldy road at about at least twice the 35mph speed limit, came rippin up to the stop sign and threw out the anchor, only well.....right across the road and crash bump bam, down the power line inspection trail it went.