The main limiting factors here are battery life, card capacity, and heat. Batteries don't last all that long in GoPro cameras, so if you're using a large card or shooting a low quality, you'll likely run out of juice before you hit any kind of limit. If you're recording at high-resolution and high-framerates, then you'll likely bump into issues with card capacity. Sure, microSD cards are relatively cheap now, but 4K footage eats up space very quickly, especially if you're shooting at 60 fps and beyond. Lastly, you'll have to worry about heat. If you're shooting at high framerates and resolution, the camera will build up heat and may shut off if you don't give it a break. The camera will always tell you how much footage it could record onto the storage you've inserted, but that doesn't account for heat or batteries. In total, you can expect anywhere from a half hour up to several hours depending on your storage, settings, and conditions.