I asked this same question about 12 months ago and we are working on reducing meetings, making them more effective, and increasing the amount of time to get in a flow state for deep work. Just wanted to share as that is where I ended up and currently playing with work analytics from the calendars on a personal and business level with a few public companies (https://execution.com/free-meeting-stats/).

Productivity is a hard one, as there are hard increases and soft ones that make people feel better which then translate into better results.