After the game's 5-year time skip event, you'll be able to receive Advanced Drills from your students. If your former students have higher skill levels of the Skills they’re proficient with, they will be able to teach you and boost your skill exp. Similar to Faculty Training, this will cost one Activity Point as well.
Students with lower skill exp than your own won’t be able to give you Advanced Drills instructions. This will also apply to former Instructors that became your allies/students prior to the timeskip. Your former instructors will be affected by this new system and the Skills they can teach you will be reduced depending on your skill levels. You’ll still earn Support points from your students during Advanced Drills.