When riding in a staggered formation, what are the safety spacing rules relative to other riders?

1. 1 second behind the rider in the adjacent lane, and 2 seconds behind the rider directly in front of you in your lane
2. 2 seconds behind the rider in the adjacent lane, and 4 seconds behind the rider directly in front of you
3. Half a second behind the adjacent rider, and 1 second behind the rider in front
4. There are no specific spacing rules as long as everyone stays in the lane