One of the best scripts I read had one glaring flaw: the hero’s best friend was a therapist, and diagnosed his problems with insight. Audiences hate therapists. They do our job for us. It always feels like the writer is inserting himself or herself into the story to tell us what's really going on psychologically. We want to be the ones who figure out the subtext.
Everybody loves Psycho, but everybody hates the last scene, where the therapist arrives and explains what it all really means.
I recommended to that writer to have the friend just be a normal schlub, giving amateur advice filtered through his own needs, prejudices, and flaws.