I'm amazed apple has got by with a 3/4 day charge for 10 generations while garmin has had products with a 7+ day charge for years.
Ultra has better battery life, most people don’t wear a watch while sleeping, so it’s easy to charge at night like you do with a phone anyway. It also enables you to do almost everything essential in terms of communication without a phone if you want to leave it. Garmin watches do not.