Programmable blueprints: how to abort?

I’m studying “Programmable blueprints”. Works well.

Question: how can the code serving a particular pattern (like “‘blueprints’ => [‘pages/notes’ => …”) abort, so the cenventional mechanism takes over again? I.e. as if the flow hadn’t been intercepted by the programmable blueprint mechanism. Neither null nor false did the trick.
This situation can arise if the pattern for some reason is not specific enough.

And just for understanding: I’m surprized that the programmable blueprint code gets executed multiple times when opening a panel page. $kirby->path() tells me that some of the calls come in via api/pages/… Doesn’t make a lot of sense to me. Is that intenional? Or might something be wrong in my setup?

I guess I found the answer:
you can to return a string containing path and filename of a blueprint, e.g. “site/blueprints/pages/default.yml”. At least that’s close to what I had been looking for.