That said probably it depends of how big the idea is and how many people are required to implement it, so the number of people it's really an illusion.

Relative to that, other interesting data would be to know how early before it was obvious did they go after their idea and if that gave them time to make mistakes and correct them. Minimizing time-to-market, that works probably in favor of no matter how many are the founders.

Thus, as the number/quality of founders decreases so the earlier your implementation should get or be feasible to get to the market.