Funnel optimization

We regularly hear the suggestion that the funnel should be optimized from the end. And this is explained by the fact that at the end of the funnel there are the most loyal and most interested users, who are a little bit short of a deal.

In general, this is true, but there is one, very significant, but. The funnel should be optimized not from the end, but from finding the point of growth.  

The fact is that not all stages of the funnel you can improve, in addition, those that can improve require different efforts to improve, and therefore optimize the funnel should be optimized from the process that gives the best effect at the lowest cost of improvement.