Most workers view the prospect of a two-hour meeting with the same enthusiasm as Prometheus awaited the daily arrival of the eagle, sent by the gods to peck at his liver. Meetings have been a form of torture for office staff for as long as they have pushed pencils and bashed keyboards.

One eternal problem has been their inefficiency. In 1957, C. Northcote Parkinson, an academic and legendary writer on management, came up with the law of triviality, that “the time spent on any item of the agenda will be in inverse proportion to the sum [of money] involved.” In that same spirit, this columnist would like to propose an even broader principle, applying to gatherings of ten people or more, and immodestly called Bartleby’s Law: “80% of the time of 80% of the people in meetings is wasted.”

Various corollaries to this law follow. After at least 80% of meetings, any decisions taken will be in line with the HIPPO, or “highest-paid person’s opinion”. In short, those who backed a different outcome will have wasted their breath. Perhaps because they are aware of the futility of their input, fewer than half of the people in a large meeting will bother to speak and at least half of the attendees will at some point check their phones.

Part of the problem lies in the paradox that, although workers hate attending meetings, they loathe being excluded even more. Nothing is so likely to induce paranoia than a department meeting to which you are not invited. To avoid this fear, managers are tempted to invite as many people as might be interested.

Clearly there are occasions when everyone should be involved: when a significant event occurs such as a change of leadership or strategy, or the announcement of job losses. If workers are organised into small teams, there is much to be said for the “morning huddle” in which members update each other on their progress; the whole thing can take 15 minutes.

But most meetings drag on for much longer. Maurice Schweitzer, professor of management at the Wharton School of the University of Pennsylvania, says they work best when preparation is done. Informing people of the agenda in advance keeps them from being caught off guard—surprise often leads to a negative reaction to plans. Sadly, he adds, preparation is not a sexy part of management so seldom gets done.

One prerequisite is to establish if the meeting is designed to persuade the staff to go along with a management decision or to learn about the workers’ ideas and problems. If the former, then allies of whoever is in the chair should speak first, and drive the agenda. But such meetings ought to be rare in a well-run firm.

If a meeting’s object is to learn what people think, a new approach is required. Low-status employees should be encouraged to speak, says Mr Schweitzer, and there should be a “no interruption rule” so they cannot be intimidated. Another option would be to let people submit views anonymously in advance.

The danger of a “no interruption” rule is that garrulous colleagues might make such meetings extremely lengthy. At one point, every worker will have lost patience with “Tommy Tangents” (those who drone on at length about an issue that is irrelevant to the agenda) and “Hearsay Harrys” (those who cannot tell the difference between a personal anecdote and scientific evidence). So Bartleby would favour limiting all interventions to a maximum of 2-3 minutes.

The best way to avoid Parkinson’s law of triviality is to get the agenda right. Jay Bevington of Deloitte, a consultancy, says there is a temptation to leave the most important—and therefore the most contentious—items until the end of the meeting. Instead they should be tackled at the start.

Furthermore, there is no point in holding a meeting unless everyone knows what has been decided afterwards. Mr Bevington says that many would be surprised how many board directors leave a meeting without being sure of what has been agreed upon.

But perhaps the best solution to tedious gatherings is to have far fewer of them. GE’s new boss, John Flannery, has called for “little or no meetings where possible”. Thanks to the miracle of modern technology, messaging groups allow management and employees to keep in touch. Information can be imparted in succinct form and those who are not involved can ignore the messages and get on with their work. Next time a manager is tempted to call colleagues together, they must have a good answer to the question: “Is this meeting absolutely necessary?”