CNNMoney calls Irwin Gotlieb, CEO of Group M, the world's leading full service media investment management company, 'the $59 billion man'. He lead the integration of WPP's media-buying shops to manage over 16 percent of the world's $364 billion in global advertising spend in 2007. Irwin knows a thing or two about leadership challenges.

So what does he see as the big challenge? The single issue that defines a successful leader? Simple: scale.

"You run a good burger joint. I'm asking you to run McDonald's," he says in this week's program on modern leadership (which I've titled 'call of duty' in a lame attempt to impress my 11-year old son).

He's not alone. I asked Rolf Habben-Jansen, Global CEO for logistics and supply chain provider Damco, about his 'favourite' mistake - the error from which he learned the most. With characteristic candour he admits that back when he was a site manager, his team got into a "real deep"crisis. "Essentially," he says, "because I tried to do everything myself."

In his current role, Rolf has overseen the merger between Maersk Logistics and Damco. He removed two layers of management, increased the sales force, and has reaped the rewards of a ruthless focus on execution: Damco figures are up despite brutal trading conditions in that sector. Lesson learned.

So why isn't this issue, the ability to think in multipliers being a vital first rung on the leadership ladder, better covered in business lit? I've read about the power of delegation, but scale is more than delegation (delegate 2.0, perhaps, if we're looking for some new spin on an old ball).

Scale means looking not just at how someone else can do one or more parts of your daily tasks, but at how every part of your daily tasks can be broken down, measured, and managed. And how you can remove yourself from them to focus on the core tenets of leadership: on growth, team building, and vision.

Brilliantly, examples of effective scalability planning are (normally) close to home. Look at your technology architecture. Can you apply that thinking to your role?

What do you think? Is an understanding of scale vital to becoming a leader? Can you share some examples of where you, or somebody else, got that step change right?