I work in a public high school, and our grades are posted without delay, e.g., on the students' last day, which is the day after the students' last exam. My kid goes to a private school, and I know that the teachers work three days after the kids. The report cards, nonetheless, are delayed by 2-3 weeks. I'm sure the grades are long done, and the delay is a means to minimize drama and negotiations about grades. Look out for grades being posted on a Friday too.