There are two steps where you optimize your funnel: the beginning and the end.
Yes, your funnel might be too long or leaking users in the “add to cart” step, but even if you have a horrible payment system, if people are interested in buying, they will figure it out how to do it.
Waiting on a 30 people line for a piece of chocolate cake is not exactly fun, but people will do it if the cake is delicous.
At the beginning of your funnel, when a user sees your ad for the first time, that’s the perfect moment for optimization. You don’t want them to just click on the ad, you want them to share it.
By encouraging the user to share your ad (aka content), you are reaching more people with the same ad dollar. The more people you reach at the top of your funnel, the more chances are to have more conversions.
The other most important step to optimize is also the most expensive: the last step. Once the user completes the whole journey, if she feels satisfied with the entire process, she will be eager to share it with their friends.
This last-mile-optimization approach will send more people to the top of the funnel. The more people at the top, you get the idea…