But, not all behaviors are this clear cut. Some have multiple causes. Started back in the late 50 s by Fritz Heider. He came up with the idea of Na ve psychology. Both of the big attribution theories follow from this principle.
Unusual behaviors lead to more inferences.
Getting a different grade so assume student complimented instructor in order to get a better grade. If all are there, then there are too many unique effects. Not going to assume anything. If it happens all or most of the time, the behavior reflects a lot. Mac Arthur found that people tend to ignore consensus information.