Too often, for sure. There's also situations --
Joe Roman comes to mind -- of cops being punished for things that no non-cop would be punished for. Taking a gun away from a crazy kid instead of shooting him?
Then there's Charley Adams getting punitive transfer for apologizing about the sliming of a murder victim. (And Huffman's explanation was bull; she could have repeated the perps' excuses, if she felt she had to, and followed it up with, "but, of course, we do hear many fanciful excuses from suspects, after all.)
But, yeah, I think there's 'way too many "isolated incidents."