Baseball

Attempting to head off the rule changes, players & managers "self-policed" the year before the change and shaved 7, 8, 9 minutes
The 24 is on top of that.
If we take average game time for THREE years prior to the clock, the difference is closer to 34 minutes.
The clock (and some other rules) has had a substantial positive impact.
Believe it or not though, game times are still nearly a half-hour longer than in the 50s through the 70s.
Games FLEW by then.
The Cubs had a pitcher named Bill Hands. It was rare for a game he pitched to last much more than 2 hours. He caught the ball from the catcher and was in the set position instantly. Guy really moved!