Think about the path a single client document takes today. Someone receives it, opens it to see what it is, decides which client it belongs to, renames it so it matches the rest of the folder, and files it. Five steps, every time, for every file.
Collapsing the steps
When documents organize themselves on arrival, those five steps become one: the document shows up already named and already attached to the right client work. The person who would have done the filing instead picks up at the point where judgment is actually needed.
Consistency you do not have to enforce
The reason firm folders get messy is not carelessness. It is that consistent naming depends on every person following the same convention under deadline pressure. When the naming happens by rule instead of by hand, the folder stays consistent on the busiest day of the year, not just the quiet ones.
The payoff during tax season
The value is largest exactly when capacity is smallest. In the weeks when documents arrive fastest, the organizing keeps pace on its own, so the backlog you used to dread does not form in the first place.