In some cases you may notice that video is choppy when playing back higher resolution videos that have been downloaded through the GoPro App and played back on a phone. Some phones can have a difficult time playing back high resolution video smoothly. If playback is choppy, the actual video file is likely fine - it's most likely just a playback issue on a specific device which will likely play back smooth on other devices or video editing applications.
If your environment is totally based around mobile devices, start by testing with 1080-30 videos and work your way up to the highest possible resolution that will work on your device.
For more information, check out these articles which have charts displaying the resolutions that certain phones may have a problem with.