First law of worker entropy
One of Buxton's laws of worker entropy, which predicts that, except in Switzerland, the probability of a meeting starting on time can never be 100%, and as the number of scheduled participants increases, trends to zero. Furthermore the more participants there are the more retarded the starting time (and content) of the meeting will be, meaning there is an upper bound on the total number of people possible in a viable meeting of a given duration.
This is because the distribution of arrival times to the meeting is asymmetrically distributed (while no one arrives early, some people arrive late), and experienced meeting participants know of this asymmetric distribution and therefore time their own arrival to the expected functional starting time of they meeting, which in turn further retards that average start time.