I've been using Moment (https://inthemoment.io/) for about a year and am really proud of how I've been able to reduce total screen time from 4 hours to 45 minutes per day. Most of the gains were due to deleting Safari and Twitter from my device (Moment breaks down app usage based on battery usage).

To anyone reading this, be aware of how grabbing your phone in the morning to read headlines or Medium digest can turn into 30 minutes or even an hour. Think about how checking e-mails can take you completely out of context and badly dilute the quality of your work. Consider how the amazing small interactions with other people that make life beautiful can be destroyed by even a glance at the phone.

Monitoring phone usage and actively cutting it down I really feel has improved my quality of life. Now that Apple has built in tools to do this, I hope more people will treat this as seriously as they treat exercise, nutrition, etc.