What a 50 minutes timer is for
Fifty minutes is the "therapy hour" and a popular deep-work block with a ten-minute break to round the hour. The page loads with the countdown already set, so the whole interaction is one click.
The timer runs on the browser clock, not a server, so it works offline once the page is open and it keeps counting in a background tab. At zero it plays a short chime; keep the tab unmuted if you plan to walk away.