Expert coaches uniformly avoid overloading performers with too much or too technical information. They tell the performers one important thing they noticed that, if changed, will likely yield immediate and noticeable improvement ("I was confused about who was talking in the dialogue you wrote in this paragraph"). They don't offer advice until they make sure the performer understands the importance of what they saw.

I say "in most cases" to allow for situations like playing a piano piece in a recital. I don't want my teacher or the audience barking out feedback as I perform. That's why it is more precise to say that good feedback is "timely" rather than "immediate."