The funnel is a useful abstraction that is routinely mistaken for a description of behaviour. The difference matters because plans built on the literal reading tend to fail in predictable ways.
What the model actually represents
The funnel describes a population getting smaller at each stage. Many people are aware, fewer consider, fewer still buy.
It is a statement about proportions across a group, not about the path a single person takes through it.
Read as a description of aggregate structure, it is accurate and useful. Read as a route, it is wrong for almost every individual.
Real purchase behaviour is not sequential
People re-enter earlier stages constantly. Someone close to buying returns to comparison, then leaves, then arrives ready to purchase weeks later.
Many purchases skip stages entirely, particularly low-value repeat buying, where recognition and purchase happen in the same moment.
Others involve several people at once, each at a different point, which the model has no way of representing.
The mapping to channels is the common error
Plans routinely assign a channel to each stage, with video for awareness and search for conversion, as though channels operate at fixed depths.
Channels are delivery mechanisms and can perform any role depending on the message and the audience within them.
Assigning a channel to a stage means its performance is judged on the stage's metric, which is how upper-funnel activity ends up being measured on clicks.
Stage metrics create local optimisation
When each stage has an owner and a target, each owner improves their own number, and the improvements can conflict.
Cheaper awareness can be bought by reaching people who will never consider, which improves one metric and degrades the next stage silently.
The failure appears at the boundary between teams, where nobody's target covers the handover and nobody is measured on the total.
What the model is still good for
As a diagnostic, it works well. Volumes at each stage indicate where the largest proportional loss sits, which is where attention should go.
A business losing most of its prospects between consideration and purchase has a different problem from one that few people have heard of.
Used that way it directs effort. Used as a plan of sequential activity, it fixes budget into a shape that customer behaviour does not follow.