Fast. What time is it? If you're like most of Apple's customers, watch the top of the iPhone, iPad, or Mac screen. Or, your watch. Fair enough. Counting the local time is about as easy as it comes in the 21st century.
Quick. What time is it in London? Or, Tokyo? Or, Dallas, Texas? That's when a world clock can be useful except that even on the iPhone and iPad it's not handy (the World Clock is stuck in the iOS clock app). On Mac, well, you need an app for it.
Time is money
In this case, the world time for your Mac menu doesn't get much work and just a few dollars with the App Clockey. It is a world clock treatment that allows you to park a number of different times and time zones in the menu bar.
What could be easier?
One click gives you a list of times and time zones around the world. Create a favorite list of times and places for quick access. Everything is visible in the menu bar. Clockey even has customization options and works with both light and dark themes in MacOS Sierra.
Even better, Clockey does exactly what date and time the Mac system settings do not. You are stuck with the basics and not much more.
What is missing in Date & Time is exactly what you get with Clockey. It's a world clock, so it exceeds time zones and shows you the city and local time you need without having to make a mental calculation. Not bad for a few dollars.
What I miss with Date & Time on Mac is exactly what I get with Clock on iPhone and iPad. Options. World Clock, Timer, Alaarm, Stopwatch, and the amazing Bedtime app.
What's not to like? Apart from Apple not adding such options on the Mac, a simple third-party app picks up where Apple quit.