"I've literally worked in HR for a Fortune 500. I'm telling all of you as a matter of fu----g FACT that PIPs are not meant to be completed. HR even tells managers when they want to fire someone "okay, put them on a PIP and start collecting documentation to build a case". If you get put on a PIP what your company is telling you is that they want to fire you but don't have a strong reason yet.
I highly recommend that people don't sign a PIP if it's presented to them. Usually the company outlines the reasons you're being put on a PIP and they request your signature. If you sign it you're essentially agreeing with their points. It's like admitting that you're bad at your job. Either make edits to the document before you sign it where you dispute their claims or just flat out refuse to sign it. It will be better for you in the long run in terms of collecting unemployment and wrongful termination if you haven't signed away your position in advance.
Keep in mind, the point of a PIP is that they don't have a good enough reason to fire you yet. The PIP exists to create a case against you. That's the whole idea. People who think it's a chance to keep their job are delusional. "