While you can release feedback and collect work for individual students on each student's submission page, it's also possible to do these actions for the whole class in just one click via the downward arrow in each class row of the Markbook:
If you want to prevent students from working past a deadline or stop them from taking back their work, you can collect all unfinished work.
You can also release all feedback and answers at once here (handy for assessments - write the feedback for everyone and then release it in one go:
Finally, it also lets you require resubmission for the whole class. This can be great if you've added another question at the end of the lesson or assessment for reflection or self-assessment.