I would say my time constant for observing certain aspects of play was much shorter than his. I could see trends in 30 days that would take him 6 months, if at all. However, that doesn't mean I don't have my own set of biases that he could call me out on.
So, I would say how much information can we ask one person to consume visually, process over time, and what is their lag before their opinion moves?
The best we could ever hope for is for a coach's observational capacity to approach what the numbers tell you day by day, minute by minute. I don;'t think there is a scenario where the numbers catch up to the coach's observation.