If you don’t know the timing, you’re asking for trouble.
A concert shouldn’t go longer than 90 minutes without an intermission. So it’s essential for directors to know durations of pieces, timing of transitions, talking, and anything else that might add to the total time. Even with a format I’m familiar with, I’m going to create a spreadsheet with timing so I can plan accurately.
The same is true in a meeting – if you set a time for a meeting, you should know how long the agenda really needs – as accurately as you can predict.
Knowing accurate timing is the difference between compelling concerts and interminable ones. It is the difference between lively meetings and meetings that attendees are ready to leave an hour before they’re scheduled to.
Most of all, as a leader, this attention to timing is a show of respect for your audience, for your attendees, for your colleagues. This respect is essential to maintaining a relationship, and not showing that respect is a great way to lose the people you’re trying to reach.