When part of the ball hangs over the hole's lip after a putt, the player gets a reasonable time to reach it, then ten more seconds to see if it drops, before Rule 13.3 treats it as at rest. Reasonable time scales with the shot — a few seconds for a tap-in, longer for a putt struck from well off the green — and only then does the ten-second clock start. Drop within that window and it's holed with the stroke that produced it, no penalty; drop after the window closes and it still counts as holed, but with one penalty stroke added. The rule dates to 1963, after Don January waited nearly seven minutes for a ball to topple into the cup at the Phoenix Open; the USGA and R&A capped the wait the following year.