What you linked is the cliff notes version of the sixth amendment, and ineffective counsel. It's a pretty big hurdle to overcome and then have the convictions reversed. Theres a pretty famous case on a capital crime the defense attorney slept through some proceedings and was taking narcotics and the conviction stood
Yeah, but that's only because when he was awake he provided effective assistance. He wrote all the motions, he presented all the evidence. I've heard of a few DP sentences getting tossed because the defense failed to present proper mitigation and make all the arguments. The Susan Wright sentence was thrown out because her attorneys failed to present BWS as a mitigator. That's it. Something as small as that can do it. I'd say if Nurmi doesn't make an effort to present some character witnesses or something, that might be considered a failing to prevent full mitigation.
I sure wish AZL would pop in lol.