'Find My' is very slow to update Apple Watch device locations and often fails

Our Apple Watch Series 7 devices have SIMS. The location data in 'Find My' is almost always out of sync, often by a half day or more, and even when well within range of a cell tower. Does 'Find My' not have a periodic polling function to wake up the watch and update the location?

Does battery saver mode on the Apple Watch interfere with the 'Find My' service?

Many of the things that 'just work' on Apple devices are slowly beginning to transition to 'just does not work'. Is there any connection?