Business meetings should all be either 30 minutes of 90 minutes.
60 minute meetings end up in one of two buckets:
People wander in late, some small-talk ensues, and once the agenda gets going, people will talk extra, and without a sense of clear direction, just to fill the space. If the meeting does end early, the participants will find a way to tack on additional riders to the agenda to use the remainder of the hour.
Everyone sits down to attack a thorny problem, something that requires real brainstorming, or a meaty presentation followed by feedback and discussion. In these cases, that discussion is just getting warmed up by the time the hour is over. Most people stay late out of respect for how valuable the discussion has become on such an important topic. But eventually someone will leave hurriedly, late for their next meeting, and the group will break up without having drawn all-important conclusions and next-actions from the session.
The key insight here is that once you have even a bit of meeting experience, it's quite easy to guess which path your meeting will take in advance. So head it off at the pass, and book only 30 minutes for those type 1 meetings, which will really keep things efficient. And book 90 minutes for the type 2 meetings, giving creativity and problem-solving a proper chance to breath.
I've been running this experiment for 3 weeks and so far it's been a revelation.