Around 15 years or so ago I was approaching a red light at a busy intersection in Manhattan in a beatup 1970 Caddy convertible that I had stupidly just bought, stepped on the brake and the pedal just kept slowly fading to the floorboard! The car was slowing, but just barely, with people crossing in front! I stuck my head out the window and warned them to move out of the way. Typical New Yorkers, they didn't notice or pay attention to what I was saying. Fortunately the car did slowly come to a stop, just past the crosswalk! I put some more brake fluid in and was able to drive again. Thing was leaking brake fluid from one of the lines.
Long, long time ago, bought one of the early 1000cc HD Sportster. Drum front brake. That “heritage” thing they wallow in, no doubt.
Had been used to a Honda CB750 with a disc front brake.
Big wake up when I come up to a red light at full tilt, and nail the brake. Yep, faded out in a second or two, went halfway into the intersection before the POS would stop.
Sold it shortly after.