1h filming with 1080p then it's time to change the battery

It really depends on the setting. Additional functions such as voice control, WiFi and Bluetooth require more battery. I did a timelapse for almost 2 hours. Compared to the Hero 4, the battery performance is slightly better. But a second battery always belongs.

Approx. 45min at 4k, a little longer at lower settings.

unfortunately not long at all! at least 1 spare battery is mandatory!