Every league I work has the no inning can start after one hour rule. The problem comes with the leagues giving a 10 minute grace period to avoid forfeits, the first game going 65 minutes second game 67 minutes etc., or there being injuries (during which the time is suspended in most leagues). If you have any or all of these things, that last game of a four game set during an evening can be starting well past 'game time'. I start the clock on first pitch, but I am also very strict on getting started on time when possible, warmup times and pitches, and no stalling. Adults SP players aren't always the best at getting on and off the field.
