I lacked the self discipline tools to control my own bed times and screen time, and failed to manage either, impacting my grades.
That was an important lesson for sure, but I do think if we'd done something more phased earlier on, it would have been better. You can tell a 13 year old "You can go on the computer as much as you like on Thursday, but if you don't get your homework done and spend 3 hours doing non-screen things, you will not be allowed to next week". Not so much with an 18 year old.