The Clock app in iOS works like this in timer mode. If you start a timer for 10 seconds, you'll see the 10 for half a second, then 9 through 1 for a second each

The Clock app in iOS works like this in timer mode. If you start a timer for 10 seconds, you'll see the 10 for half a second, then 9 through 1 for a second each, then 0 for half a second, then it beeps. In practice it's pretty stupid and not really useful, so I wish they'd fix it. There's a reason why normal countdowns work the way they do. You care about the exact moment it hits zero, and with rounding you lose that. Clocks are not 30 seconds late.