A web page can't ring once your screen locks, so the Set lock-screen alarm button on each checkout hands the remaining time to your device's real Clock timer, which rings even locked or in your pocket. Set this up once:
- Open the Shortcuts app (it comes with your device) and tap + to make a new shortcut.
- Tap Add Action, search Start Timer, and choose it.
- In that action, set the unit to Minutes. Tap the number, delete it, then tap Shortcut Input in the blue bar above the keyboard.
- Tap the shortcut's name at the top and rename it exactly Crown Timer.
- Tap Done. That's it.
Now, when you hand a device over, tap Set lock-screen alarm and a Clock timer starts for the minutes left. The first time, tap Allow if asked. If you pause or switch on the desk, remember to adjust the Clock timer too — the two run independently.