In my study of how companies shorten their workdays, one of the things I’ve consistently seen is companies shortening meetings, and doing a number of things to make meetings more effective: requiring pre-circulated agendas and goals, sharing background material beforehand, having walking or standing meetings, and making sure that conference call phones and other tech are running smoothly before the meeting is scheduled to start, so you don’t spend the first 10 minutes looking for dry-erase markers or punching in conference codes.
They also use tools to signal when meeting times are up, or when the group only has a few minutes left. The most popular tools are kitchen timers and smartphone alarms (unless your company bans devices in meetings, which is another popular thing), but a couple have taken a more high-tech approach: using Philips Hue lightbulbs and some locally-sourced code to have the room itself signal when you should start wrapping up.
I first heard about this tool at IIH Nordic, a Copenhagen-based SEO firm that moved to a 4-day week, but others use it, too. Philadelphia design firm O3 World calls their RoomBot, and explains how their system works in this video:
It’s a cool system, but the important thing is to have some kind of external tool that announces when your time is up.