Do invisible fences actually stop stubborn or fast dogs?

This is the most consistent caveat across the sources we read. High-trust community threads (including r/dogs and r/homeassistant) repeatedly warn that a determined or fast-moving dog can build enough momentum to 'power through' the correction zone, and once outside many dogs won't cross back in. Reviewers broadly agree that proper boundary training—not the hardware alone—is what determines success, and that high-drive breeds are the hardest cases.