How do you know a channel is dead versus just slow?

This is one of the harder calls in go-to-market and I don't think anyone has fully solved it.

Zero results is easy. Zero means stop. The hard case is bad-but-not-zero, where something is technically working but not enough to justify the time, and you have to decide whether it needs more runway or whether you're funding a dead end.

The rule I've landed on: I stop looking at the final number and look at whether any part of the funnel is improving. If the top is growing but conversion is flat, it's a targeting problem and worth fixing.

If nothing is moving anywhere after a fair run, more time won't change it. Volume alone has never rescued a channel for me.

That's held up so far, but it's one person's rule from one set of products, so I'm curious how others handle it.

Do you use a fixed timebox or a specific metric to make the call?

And has a channel ever come back for you after you'd written it off?