I have observed in an organization where I frequently give training that 25% of the people in the course are on time regularly. The rest of the people come later, and usually by 15 minutes after the start time of the course, everyone is there and we can begin.
In this organization, meetings are the main space for collaborative work, and people can have up to 4 or more meetings a day.
In this case, for the 25% of the people who are on time to meetings (which start 15 minutes late), they lose 1 hour a day of waiting around for people to arrive and for their meetings to start.
If your staff is 200 people, then 50 people are losing 1 hour a day to late starts. If 50 person hours of work per day is being lost, that makes 250 hours a week lost in waiting for meetings to start due to late arrivals.
250 hours a week is effectively 6 staff members whose complete time is being spent sub-optimally, they could go home and get paid to do nothing.
That’s 1000 hours/month, or 12000 hours per year, which is 250 work weeks, or over 6 person years of work lost to an organization every calendar year from people who are 15 minutes late for meetings…