This. If you think of startup investments as market probing activity, then the lean startup model is an optimized version of this for specific kinds of markets.

You aren't going to make a new storage company or a new ASIC-based company in the lean startup model (though you can certainly be _lean_er_ than companies tended to be in the past or the lavishly spending mega-investment-level companies on the spendthrift side of the capital wall like Uber) but you can do a lot of probing of the consumer marketplace this way.

Depends on which way you look at. I wrote the article from the perspective of a founder, not an investor. The math analogy is a bit stretched though. Following it, the only thing that matters is where you start. If you started in the hill leading up to the global maximum you'd be good. I have no statistics to back this up, but I would suspect reaching a global maximum is more expensive than reaching a local one. Truly world-changing ideas, therefore, don't lend themselves as well to the lean methodology.

I guess it's a matter of scale, like a fractal. If your idea is big enough, it might be easy to get fooled into thinking you are at the top when a small detour might lead to a much higher summit.