When it comes to brainstorming, Amazon has a rather unconventional policy - no meeting, no matter how important, should ever involve more people than can be fed on two pizzas. This is the sort of rule one might expect from a West Coast technology group that likes to do things differently.But there is a reason behind it: the fewer the people, the better the discussion and so, the theory goes, the better the ideas.Amazon founder Jeff Bezos, who is said to hate meetings, was asked if this rule exists."Yes," he said. "Mentally, we're a start-up. We have a lot of scale in certain areas that's not like a start-up, but we still want to invent like a start-up."It's a rule that has stood Amazon in good stead. Last week the technology giant unveiled its latest venture, a music-streaming service aimed at challenging Spotify and Apple Music.This isn't the first time it has tried to compete in the digital music market. In the recent past it tried to steal Apple's iTunes' download crown but this time it has an arguably better proposition, linked to its popular Prime subscription service.The success of this venture would send shock waves through the music industry . But Amazon says it is merely another product.The day before it launched Amazon Music Unlimited, plans for a move into bricks-and-mortar grocery stores in the US by Amazon emerged. Under what is said to be known as "Project Como" internally, Amazon will complement its existing Amazon Fresh food-delivery business with shops at which people can make purchases or collect Fresh orders.It recently launched Echo, its voice-controlled artificial-intelligence speaker.Just before that, it was its "Dash" buttons, which can be placed near bulk-bought items in the home such as toilet rolls or washing powder and allow automatic reordering.Before that, it was the launch of Amazon Restaurants delivery service. And before that, it was the launch of Amazon Fresh.Each launch is well orchestrated, thought through, and planned precisely.There is no assumption that each new business will be a leader in its field, or that it will be profitable in the short or even medium term.And that's the point. The more business streams Amazon can be in, the more pervasive its name becomes, the less important it is if its core online ordering service is propping up its fledgling TV production business.The sheer pace at which Amazon can generate and unveil a range of developments is attributable to the volume of workable, innovative ideas flowing from its employees.Two pizzas might seem like a tiny amount of food, given Amazon's 230000-plus employees, but that is exactly the point.For behemoth Amazon, thinking like a start-up is what keeps it growing.The price of those two pizzas is well worth the investment. ..