At the end of the 19th century, the French agricultural engineer Maximilien Ringelmann investigated the group behavior of people. He had test participants take turns in pulling heavy loads either alone or in teams. However, the larger the number of people that were pulling the weight together the more they reduced their individual efforts. While a “lone fighter” managed to pull 63 kilograms (139 lbs.) on a rope, that weight decreased to 59 kilograms (130 lbs.) per individual in a team of two. With three people pulling, the per-capita weight dropped to 53 kilograms (117 lbs.). The larger the number of weight pullers the smaller the effort expended by any individual.

While Ringelmann still explained this correlation with difficulties in coordinating the pulling effort as identically as possible, two other scientists in the 1970s found out that the effect even occurs when the test participants are pulling on a rope by themselves while being blindfolded and merely believing that they’re doing so as part of a larger team: the larger the assumed number of people on the team the smaller the performance delivered by the individual.

However, those experiments also showed that the more a group grew the more the Ringelmann effect receded: The differences between teams of two and five were still massive but whether six or 15 persons were pulling on the rope hardly made any difference in terms of the individual’s willingness to perform. Is that good news for large teams? Not necessarily because as soon as team members also need to communicate with each other there’s an additional problem.

Growth as a fire accelerant

In the early 1960s, American computer corporation IBM put all its eggs into one basket: The new System/360 mainframe series was to become a success at all cost. The company invested a humongous amount of five billion U.S. dollars into its most important project. Responsible for the operating system of this new mainframe series was the talented mathematician Frederick P. Brooks, who became the boss of an initial number of 150 programmers.

However, the schedule was far too tight. While hardware development, which required minimal coordination between the engineers, was making good progress, the software was lagging behind. Brooks constantly had to expand his teams because schedules got out of hand.

However, with each new member the performance of the individual teams deteriorated and their code included more errors. “It was like dowsing a fire with gasoline,” a frustrated Brooks found. Finally, after 5,000 man-years, the operating system, on which more than 1,000 people had been working during peak periods, was finished – and Brooks had gained a wealth of experience.

He later summarized his findings in a much-noted book titled “The Mythical Man-Month.” Brooks’ law (named after him) that’s captured in the book says that adding manpower to a late software project delays it even further due to the effort required for onboarding, definition of interfaces, and additional coordination rounds.

Brooks’ conclusion: The larger a team the faster the growth of potential communication channels between two people, respectively. In a team of three, there are only three possible pairings for direct dialogs (Person 1 with Person 2, Person 1 with Person 3, Person 2 with Person 3). In a team of ten, more than 50 are possible and in a team of 50 far more than 1,000.

“Telephone game” on the job

That has serious repercussions: Even agreements that shortly before were jointly made in a large team round are typically corrected in countless smaller rounds or verbally communicated incorrectly shortly afterward – just like in the popular children’s game “Telephone.” Because, in real life, all the members of a 50-member team never meet at the same time, every piece of information wafts through a huge echo chamber of post- and post-post-discussions.

Julia Meyer is responsible for workplace performance in the production systems function at Schaeffler. She ensures ergonomic and efficient workplaces in plants of the Schaeffler Group: “With methods like our Team Improvement Program TIP, we provide our locations with a tool to strengthen teams on the shop floor.”

Despite state-of-the-art communications technologies she continues to see an upper limit of ten workers in a shop floor team. Teams in other areas, for instance those with a lot of business travel, should ideally be smaller, according to Meyer. Her own team has six members.

Explosion of friction losses

Surprisingly, what was true in the day of Brooks and the punch card with its sparse opportunities for communication is still true today in the age of team meetings and constantly connected workplaces. “We have so many communications channels, but when I have a large team it’s difficult to concentrate them,” Meyer warns.

That’s why Mariana Krištofová is focused on ensuring smooth communication between her team members and with managers in accordance with the Schaeffler management principles Transparency, Trust & Teamwork. She has a degree in mechanical engineering and at Schaeffler leads the Special Machinery team with 170 employees at the Kysuce location: “The key prerequisite for large teams to work together well is effective communication, teamwork, and mutual support.”

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The Invincibles

What could a perfect superhero team look like? The AI of Microsoft Bing recommended this eight-member mix of various characters:

The leader Charismatic and inspiring, with a strong moral compass.

The genius Highly intelligent, a master of technology and strategy.

The powerhouse Incredible strength and stamina, often the protector of the team.

The speedster Superhuman speed, can act and react in fractions of a second.

The shapeshifter Can change their looks, ideal for espionage and deception.

The telepath Mind reader and influencer, useful for communication and gathering of information.

The elemental Control of elements such as fire, water, air, or the Earth

The healer Can heal injuries, is indispensable for the team’s regeneration.

Only if that’s ensured larger teams are basically feasible, according to Krištofová. “From my experience at Schaeffler, I’d say that there’s no such thing as a ‘magic number.’ I’ve worked in larger and smaller teams. For instance, I’ve got fond memories of working in a 20-member team in which communication and collaboration worked out 100 percent,” she says.

Unfortunately, that’s not the rule in the world of work. Professor Florian Becker from the Business Psychology Society has been engaged in research about leadership, motivation, and teamwork for many years. He knows that, “In excessively large teams, friction losses virtually explode. The larger a team becomes, the more dysfunctional dynamics such as coordination efforts, conflicts, lack of clarity about roles and responsibilities, and social freeloading increase.”

His advice: “Make your teams only as large as necessary and keep them as small as possible. In most companies, five will be a good upper limit for people that are supposed to work together in close coordination and in self-organized ways.”

Plus, large teams pose a problem to leaders as well. In the case of more than ten team members, there’s often not enough time for onboarding new colleagues or for personal exchanges.

Small teams, though, have a problem too because aside from their size their composition is at least equally important. In the 1970s, British researcher and management consultant Meredith Belbin identified nine different team roles in successful teams such as “shaper,” “implementer,” “coordinator,” “plant,” “specialist,” “monitor/evaluator,” and “team worker.” Theoretically, individuals could assume several roles, but a “resource investigator” isn’t necessarily a good “perfectionist.” That’s why teams that are too small often lack important specialist skills. In that case, larger teams tend to have greater potential.

So, is there a magic formula for team sizes? Unfortunately, not. That said, there are some rules for successful teams. The right team composition and the right team size are still some of the key success criteria for successful work.

At the end of his project, IBM mathematician Brooks was able to deliver a functional operating system. In the first Lunar landing mission, NASA relied on System/360 and successfully sent a three-member team of astronauts to Earth’s satellite and back. However, that mission was only possible because another 400,000 people on the ground made their very personal contribution to it. Perhaps that’s one of the secrets of efficient teamwork: the conviction of working together on a good project.