To answer your question, in my years of practice, I had always been careful in advising colleagues about their diagnosis or plan of care for their patients. Talking about errors can be challenging. But if it is to enhance patient safety and improving the quality of service, although it would be uncomfortable, choosing the right approach would be crucial.
So far, in all the different rehabilitation facility I had a chance of working, communication was always encouraged. Therapists would seek each other for advice if they were unsure of something. And like you said, monthly case conferences or staff forums facilitated feedback on every aspect of patient