Return of Serve must clear the NVZ

4.N. Receiver Faults. It is a fault against the receiving team, resulting in a point for the server if:
4.N.1. The receiver or their partner is touched by or interferes with the flight of the ball before it bounces.
4.N.2. The receiver or their partner calls a time-out after the serve has occurred.
  4.N.3. The Reciever hits the ball, and it lands in the non-volley zone, which includes the NVZ lines

4.N. Receiver Faults. It is a fault against the receiving team, resulting in a point for the server if:
4.N.1. The receiver or their partner is touched by or interferes with the flight of the ball before it bounces.
4.N.2. The receiver or their partner calls a time-out after the serve has occurred.

The "Two-Bounce Rule" effectively requires the non-serving player of the serving team to stay back by the baseline to ensure there is room for the ball to bounce with a deep return.  This creates a somewhat common scenario with an indefensible shot when the ball lands in the NVZ.

The most egregious example is when the returning team drives the return a bit low, hitting the top of the net, and it plops dead in the kitchen on the other serving team's side.

There are a few other examples I've seen, but I feel this example is the most indicative of the problem since there is just no defense against a dead dink on the return of serve.

The learning curve for both existing and new players should be minimal. Existing players rarely intentionally hit a return of serve into the NVZ as they "should" be trying to keep the serving team back, and new players can be easily taught this as a component of the 2-bounce rule.

Every start of a rally when returning the serve.