Not hard, visualize the locations on the globe and a pie with 24 slices. If you start work at 12, and you want to know when someone 2 slices West will start you add 2 to get 14. 2 slice East of you, subtract 2 to get 10.

Better than guessing what timezone the region picked when it spans multiple natural time zones, and whether they do or don't have time changes.

Also it's much easier for communication, because if someone sends you a message asking to have a call or meeting at X hour there's no need to know their timezone, because your X hour is the same as theirs no matter where you are in the world.