I worked within the TechStars business incubator when I was starting my marketing consultancy. I saw 3 whole cohorts go through the program, and the start of the 4th cohort.

The owner of TechStars was a client of mine, and he had his business housed in the same work loft as TechStars. So I wound up being the "in-house marketing consultant" for all the TechStars founders and projects.

I got to see a number of big name projects in their very infancy. The best ones always had 4 people at the core of the project as co-founders. One person is too myopic. Two people argue. Three people just kind flail around each others' orbit.

But once you have 4 people, each person has a 'reasonable' amount of work to do (<70 hrs/week), and there are three other people you can "team up" with to tackle specific problems, depending on their area of expertise. ALL of the 'winning' projects from TechStars had 4 people at the core.

Although, once launched, those projects would quickly lose two founders, and gain employees instead. There always seemed to be two founders who had little interest in running a company; they wanted to build shit, and not be confined. So they'd be bought out, or become silent partners and pursue other interests.

It was a cool environment to be in.... got to hang out with Sir Mix-a-lot, even!