Roads tend to allow two vehicles side by side. In addition to giving a 5 sec pause for the following vehicle, try putting one on the RHS of the road and the 2nd on the LHS, and stagger any additional vehicles that are following. Of course the issue is that additional pauses are not every 5 seconds but increase exponentially to 45 seconds.
So, in addition to increased PAUSES, the other technique I use is to have following vehicles drive at a slower speed at least until the first waypoint. So, if the first Vehicle moves FAST, later vehicles could move QUICK, then HUNT etc.