Paul Corfield wrote:

I would imagine it would be true if the zones on the travelcard did not
cover the journey to be made.

On a side note are there any plans to put Willesden Junction back into Zone
2 (or at least shared)? It's only been about ten years since it was shifted
fully into Zone 3 and with Hampstead Heath likely to go back to 2 this
leaves WJ the sole obstacle to having Orbirail entirely in Zone 2.