26 Year Gap wroteActually, back in the 60s, I believe the bonus reset every quarter and it was on the 5th foul. However, the first four fouls were 1 shot unless a shooting foul or an offensive foul.
As a player back in the olden days, I kind of remember something like that. I was too busy playing to have any real understanding of the rules. When the official tossed me the ball and said, "One shot", I just took the ball, and shot it (it usually missed). Now that you bring it up, I do remember lots of one shot free throws, definitely a lot more than in today's game.
I hope that someone who really remembers the rule (Mark T. DeNucci, Sr., Jurassic Referee, others) can follow up on this.