Life is busy.
The proposed 3-3-3 method tackles down tasks by following these rules:

3 hours of focused work

For the most important task of the day. Has priority over everything else.
ie: assignment, projects, etc

You'll get more done in 3 hours of focused work than 10 hours of distracted work

3 urgent tasks

For urgent and less time-consuming tasks. Do the things that you have been putting off.
ie: replying emails, organizing study plan, planning project

3 maintenance tasks

For nonwork, school tasks.
ie: laundry, meal prepping, chores