Apple Watch GPS

I have a GPS only Apple Watch, and my typical range is 50 feet (15 meters) for Bluetooth.

Plus WiFi is possible, however the switch between Bluetooth and WiFi is not instantaneous, so if you are on a phone call over Bluetooth to the iPhone, and move far enough away, the call will drop before it can switch to using WiFi between the Apple Watch and the iPhone.

I have not really had any issues using my GOS only Apple Watch during the past 5 years. I also tend to keep my iPhone close by.

A GPS-Only Apple Watch can use Wi-Fi and Bluetooth to communicate with your paired iPhone. 

• Your GPS-Only Apple Watch uses Bluetooth (typically about 30 foot range) when your iPhone is near, which conserves power. 
• If Bluetooth isn’t available, your GPS-Only Apple Watch will try to use Wi-Fi (if set-up). For example, if compatible Wi-Fi is available and your iPhone isn't in Bluetooth range, your GPS-Only Apple Watch uses Wi-Fi. Wi-FI range is usually a lot greater distance and depends on your router.
• Your GPS-Only Apple Watch switches between these intelligently to choose the most power-efficient connection.

For more info, see:

About Bluetooth, Wi-Fi, and cellular on your Apple Watch - Apple Support