IIRC events were created based on some heuristic of the photos' geolocaiton data and time taken. So if you do a 3 day trip outside of your city that becomes one

IIRC events were created based on some heuristic of the photos' geolocaiton data and time taken. So if you do a 3 day trip outside of your city that becomes one event on import. It was also super easy to merge two events into one. I thought it worked pretty well in general.