This has probably already been said, but places that mandate that X% of people need to be put on performance improvement plans are not great. This can force managers (or HR, depends on who decides the PIP) to put otherwise good engineers or staff on PIP when they are perfectly fine employees - they may not be 10x, perfect, and can just be doing what they need to do to do their jobs, but they still aren't doing anything wrong and end up on a PIP because the company is forcing them to put atleast some percentage of people on it each year