The single biggest productivity gain available to most organisations costs nothing: better meetings. The difference between a meeting that wastes an hour and one that produces a decision is design - specifically, knowing the answer to three questions before you send the invite.
Purpose and outcome
Every meeting needs two things: a clear purpose (why are we gathering?) and a defined outcome (what will be different when we leave?). If you can't articulate both before scheduling, don't schedule the meeting - send an email.
A purpose might be 'Decide whether to proceed with Vendor A or B' while the outcome is 'A decision recorded in the minutes with rationale and assigned actions.' A purpose of 'Discuss the Q3 roadmap' is too vague - what specifically needs to happen as a result of the discussion?
Write both in the invite. 'Purpose: Review and approve the project charter. Outcome: Signed charter or list of required changes.' This lets attendees prepare and signals that the meeting has real stakes, not just a slide deck to sit through.
Designing the agenda
Once you know the outcome, work backwards to design the agenda. Each agenda item should be a verb - Decide, Approve, Review, Generate, Align - followed by the time allocated and the preparation required. 'Decide vendor selection (15m, pre-read: scorecards in shared drive)' is a usable agenda item. 'Vendor update' is not.
Timebox ruthlessly. Parkinson's Law says work expands to fill the time available. If you allocate 30 minutes for a decision, it will take 30 minutes. If you allocate 10, people will find a way to decide in 10. Start with the shortest reasonable time and extend only if the discussion demands it.
Send the agenda 24 hours in advance. A meeting where attendees see the agenda for the first time when they arrive is not a meeting - it's a performance. People need time to form thoughts, check data, and prepare questions. Respect that time and you'll get better decisions.