No honey, that IS how GPS works. Triangulating your position via GPS requires connecting to no less than three satellites. Your smartwatch does not have GPS active 99% of the time. It's getting location data by mostly by looking at cell towers and WiFi networks nearby, and only uses GPS very sparingly. If your GPS was constantly active (which is what you would want when trying to catch a lost dog) then your smartwatch battery would be dead within hours, not days.

Your Garmin runs on AA's for weeks because it's not TRACKING anything, it's just showing your location on a map, locally. It's ONLY using GPS and not using any sort of data connection. The energy required to constantly check GPS and constantly report back a device's location via LTE is actually quite a lot, even if you only check in every five minutes. This is why GPS trackers only last a couple days unless they have a big battery. And this is why AirTags are popular; they last a long time because they don't use GPS and they don't need a data connection.