I think its important to remember its a accident recorder, so really you do not need to document your 4 hours of driving before the event, with good timing all you would need is the one 3 minute file.
Of course if you go for a nice scenic drive then you could use dashcam footage as a journey video, bur really they are not ideal for this job due to their large FOV
Also you dont really want to save all your driving, that would just eat up hard drive space, and really if nothing happen then its just driving and pretty uneventful.
If it wasent for the 1 second overlap then you could just drop XX 3 minute files into any editing program and output those as 1 file with a few clocks of the mouse, but the 1 second overlap in between segments ruin the viewing pleasure as you have 1 second repeated every 3 minutes.