You have a good point, but there is another aspect of content and learning that needs to be considered. Simply equating class tests to standardized tests missing an important difference. Class tests often cover content that students have been newly introduced to, and that they might not have completely mastered yet. Standardized tests cover content that all students should have mastered already. Here, it seems that homework might be most helpful as a means for students to “practice” what they might already know, so that they sharpen their mastery of the content. On the other hand, using homework as a means of introducing and reinforcing understanding of new content might not be the best approach. With new content, manyh questions from learners are common, questions that require interaction with a teacher. Homework is not the best option when teacher interaction is necessary for students to understand and move on.

All the best, RHT

But the analysis found a positive association between student performance on standardized tests and the time they spent on homework.”

This would seem to not make sense to me. Standardized tests and class tests are different, but the effects should be the same. Where I grew up, completed homework assignments counted towards your grade, so if you did not complete any assignments for the class, the best you could do was a D in most cases. Yet they say there is no difference in grades, so therefore homework is not included as a grading factor, leaving more weight for tests. Then if there is no difference in grades with tests being the weight, how can a student show improvement on tests, but not get a better grade?