Set your first limit

Open Precursor and tap "Allow Screen Time access" when asked (this is what lets Precursor block apps).

Make a limit group: tap a group, tap Choose, and pick an app or two you actually use.

Set an allowance, like 5 minutes per hour. Make a few groups if you like; each one blocks and resets on its own.

Tap Start limits. Use the app until the allowance is spent and you'll see a calm block screen showing when your time comes back.

At the top of the next hour, the block lifts and your minutes reset automatically. That's the whole rhythm.