Leach relays are used extensively on all Boeing, Airbus, Douglas, and Gulfstream aircraft. They can be found in numerous other types of corporate aircraft.
They are extremely reliable as they can last numerous decades with thousands of cycles.
Years ago, I encountered a relay from a Gulfstream that was acting like the car blinkers of old. The coil would get hot and go open which caused the relay to relax. As soon as the coil cooled, it would energize again.