But in advertising, sharing the power is becoming a new vogue.
So how do you make having more than one person in charge work? As one agency chief executive comments: "The only way an operation can be run by two people at the same time is if there is a complete absence of ego, and you don't get many complete absences of ego in the advertising game."
What's more, bosses don't come cheap. You could usually buy a few middleweights or a skipful of juniors for the price of one boss. So why would any company want to pay for any more bosses than it needed?
Dual appointments arise from a number of circumstances. There's the hedged bet, where it's unclear who's best for the job but it's likely that one will turn out OK in the end. Or the resignation blocker, where the job is offered to two close rivals to stop one of them flouncing off in protest.
Then there's the political marriage after a merger, where a representative from both sides is needed to steady the ship. Sometimes there is no one person who is sufficiently equipped to do the job alone, and so the load has to be shared out. Or there's a concern over keeping major clients happy by installing "their man" in the number-one spot, even if there is more than one number one.
Circumstance forcing the situation is behind many senior joint appointments.
But are there cases where two heads are genuinely better than one? It can certainly be made to work - after all, most agencies began their lives as joint and equal partnerships - and there are upsides. There is strength in numbers when you are vulnerable and on a steep learning curve. For every extra boss, there's another 24 hours of executive time each day that can be spread around the shop. And having to consider other perspectives at decision-making time can lead to more circumspect conclusions. If the chemistry's there, these upsides can outweigh the pitfalls of sharing executive power.
RICHARD FLINTHAM and ANDY MCLEOD - Joint creative directors, Fallon
McLeod (right) and Flintham don't know any other way to work. They've been a team for 15 years, going back to art college. When they helped to set up Fallon's London office four years ago, there was never a question that they would do anything other than share the creative director post.
Creative teams are nurtured as pairs for good reasons, and McLeod and Flintham have brought these to bear on their executive role. Two pairs of eyes help keep perspectives fresh. A diversity of opinion provides the all-important creative tension in which ideas flourish. And there's the question of discrete crafts. According to Michael Wall, a managing partner at Fallon: "Words and pictures are two specific skills. With both represented at the most senior level, it means that our creative product doesn't end up skewed one way or the other." The pair also bring other different attributes to the party. McLeod is strategically attuned and can grasp the creative potential of a problem with razor-sharp precision. Flintham is more organic, more randomly fertile.
Where McLeod's instinct is to hone down, Flintham's is to expand out. It forms a potent combination. But they also have to be able to operate individually. They sometimes need to take it in turns to zoom in and zoom out: when one is concentrating on the minutiae of a brief, the other has to take a broader view of what is happening in the department at large.
As Mary Newcombe, the head of marketing at Skoda UK, says: "Having two of them means that one is always available and they're also very good at judging the mood and knowing which one of them to field in any situation."
NICK LAWSON and JANE RATCLIFFE - Joint managing directors, MediaCom
When Ratcliffe and Lawson were thrown together in the wake of the merger of the old MediaCom and The Media Business in 1999, it was seen by many as an essentially political move to ensure that both camps were represented at the top table of the new agency. In truth, the pair did prove a perfect complement to each other.
Lawson's background in new business brought a ruthlessness that had earned him the nickname of The Prince of Darkness among colleagues. An ex-client services director, Ratcliffe excelled in people and relationship skills.
With the help of some professional counselling, they have forged a partnership that makes the best of what each has to offer.
Ratcliffe believes the secret is to be clear with one another and the agency about who does what. Lawson looks after marketing and new business, TV buying, sponsorship and outdoor. Ratcliffe concentrates on the internal issues of human resources, training and also press buying. The agency is split into autonomous account groups and each of these groups report solely to either Ratcliffe or Lawson.
Ratcliffe also believes that constant dialogue is key. They sit next to each other and always try to consult with each other before reaching major decisions. This can slow the process down but it can also be used as a tactic to buy time when being pressurised for a hurried response.
MATT SHEPHERD-SMITH and JONATHAN MILDENHALL - Joint managing directors, TBWA/London
The marriage of Mildenhall (right) and Shepherd-Smith came about as the result of a simple principle espoused by the agency chief executive, Andrew McGuinness: "Don't let your structure get in the way of promoting your best people." There was little to choose between the two candidates and McGuinness decided their different styles and personalities could provide a boon to the management team.
Mildenhall is more flamboyant and gregarious, and wears his heart on his (often gaudy) sleeve. Shepherd-Smith is a more classic account man: considered, affable and diplomatic. He believes that in a service industry it is increasingly impossible for one style to fit all, and that the new regime allows for a more multi-faceted offering at senior level. The arrangement is only a few months old, and they are both still adjusting to it.
They have gone from never having worked together on anything to occupying adjoining desks overnight. Some of their responsibilities are shared, others separate. Mildenhall is more outward-facing, concentrating on marketing and new-business development. Shepherd-Smith will occupy himself with staff issues and incremental business opportunities with existing clients.
These roles were clearly defined by McGuinness from the outset. They both still have accounts to run and share responsibility for the operational working of the agency and for delivering financially against the business plan.
The majority of their time is spent working together as a team, both with each other and alongside McGuinness, the chairman and creative director, Trevor Beattie, and the planning director, Neil Dawson, in the overall management group. It has required a shift in outlook. Previously as the group heads, they were in competition with each other and only concerned with 25 per cent of the agency. Now they're on the same side and looking out for 100 per cent of what's going on.
NICK HURRELL and MORAY MACLENNAN - Joint chief executives, M&C Saatchi
MacLennan (right) and Hurrell have known each other since the mid-80s and have been running agencies together for the past 12 years. In many ways, their individual styles appear to complement the other perfectly.
Hurrell is the hungry go-getter, bursting with enthusiasm; MacLennan is the polished, considered adman. Hurrell is the driving force behind the agency's diversifying beyond advertising and has even been known to go on the odd breakout weekend. MacLennan is the advertising purist, a James Bond figure more likely to be seen jumping into a Ferrari than taking part in corporate wargaming.
But these differences are superficial. At their core, there are more important similarities. Ben Langdon, McCann-Erickson's president for Europe, the Middle East and Africa, says: "They share one consistent thing: a brilliant intelligence." Barry Jenner, the managing director of Gallaher UK, adds: "They have enormous passion and are both fantastic at client handling. It is a people business and they do it consummately well." They split the agency down the middle and share all internal and external responsibilities. Their office has no door, but they make a point of saving their rare disagreements for resolution in private. They never share pitches and so the competitive nature of each ensures that energy levels are constantly sustained. It helps that they have worked together for so long and in an agency culture where joint management has always been a feature.
They have one of those relationships where one can finish the sentences of the other. But the man who brought them together, Lord Saatchi, disagrees with those who describe them as complementary: "That suggests that they are different and I think they are very similar. They are the two most brilliant advertising people I've ever met. They both have just a natural superiority."