As the op, for the case I was thinking about, it’s “couldn’t” as in “I don’t have the time to go checking file by file and the variation is not straightforward

As the op, for the case I was thinking about, it’s “couldn’t” as in “I don’t have the time to go checking file by file and the variation is not straightforward enough that grepping will surface cases straightforwardly”. I’m very much able to understand the result and test for consequences, I wouldn’t think of putting code I don’t understand in production.