Where I work, we have company-wide breaks between 10.00-10.15, 12.00-13.00 and 15.00-15.15. These cannot easily be enforced with external parties, but running an internal meeting over a break will need an explanation. What I noticed is that back-to-back meetings are more likely "capped" at 2 hours, so it's easier for people to show up on time and energized.