A turnover then or anytime thereafter was pretty much it, as was a turnover during any of the three previous plays. You can't play the game expecting to turn it over if you play anyway but the most cautiously.
Once you are in FG territory, a TO is a game reversal, game ending error.
Prior to being in FG territory, its game ending only.
Bud Adams told me the franchise he admired the most was the Kansas City Chiefs. Then he asked for more hookers and blow.