If by 'people' you mean 'humans', they were definitely in the minority. Most often we would recover people who had entered the Rift without even knowing it was there, usually from a different point in history, and...then it was our job to help them adjust to the twenty-first century. There's no reliable way to control the Rift, and absolutely no way of ensuring that if you go through twice you'll end up back in the place you came from the first time.