Does the Apple Watch need to be charged every day?

well they sure warn you about letting it get low in % is very bad for the battery

About the battery and performance of iPhone 11 and later - Apple

Support

and iPhone Battery and Performance - Apple Support

and Batteries - Maximizing Performance - Apple

"...iPhones have never been designed to be charged every night all night. That is nonsense...."

In case you didn't see my original response, it is not nonsense.

Here is some very sage advice.

User Tip by highly respected Lawrence Finch https://discussions.apple.com/docs/DOC-9732 

All Apple Watches and iPhones are designed to be charged all night every night on the recommended charger.

Unless you are prepared to turn them off for long term storage, "making them last" more than a day actually uses more charge and will shorten battery health.

The topic is the ‘latest’ Apple watches, not the previous Apple watches.

Apple claims the Ultra lasts up to 36 hours.

References for claims are essential.

iPhones have never been designed to be charged every night all night. That is nonsense.

Here you go. Here is how Apple rates the battery on Apple Watch. All watches, with the exception of Apple Watch Ultra are rated up to 18 hours. Apple Watch Ultra is rated up to 36 hours.

I own Apple Watch ultra and I still charge my Ultra at night while I sleep. If you purchase any watch other than the Ultra, you will need to charge it every day.

See this --> Apple Watch - Battery - Apple

If you intend to use it every day then it needs to be charged every day. The battery is slated to last about 18 hours with normal use.

M1 Mac mini, macOS 13.1; Watch, series 7 GPS/cellular, watchOS 9.2; iPad Pro 2nd Gen, iPadOS 16.2; iPhone 12 Pro, iOS 16.2; TV 4th Gen, tvOS 16.2; HomePods, audioOS 16.2 and Airport Express w/ Airplay 2

Is there a reference to state this is still correct for the latest watches?

I charge it everyday, yes. I have about 18-20 hours of battery life in a day