Don't use the funnel

When using a funnel (literally or in the figurative business/marketing sense) there is one variable that is relied upon but, hard to control. That variable is gravity. Without gravity, a funnel would not work. Of course there are other variables like funnel capacity, funnel width and depth, etc - but gravity, the assumption that some (if not all things) at the top of the funnel will drop is a dangerous assumption to rely on.

Well, if not a funnel, what should you use instead?
I suggest a pipeline.

A pipeline does not rely solely on gravity, but instead relies on pressure. This pressure must be applied at key points and throughout the entire pipeline. The longer the pipeline, the more pressure must be applied. So if you took your marketing funnel, and now thought of it as (or turned it into) a pipeline, where would you need to apply pressure? How much pressure? How much is flowing?

So build a marketing pipeline, not a marketing funnel. Control the pressure, don't rely on assumed gravity. Apply pressure points through specific timed tactics and content. Just remember, if you apply too much pressure you might rupture your pipeline. And nobody wants leads spewing out all over their competitive marketing landscape..