One thing I really concentrate on is holding a consistent pace and effort throughout my/our rides. I've passed so many riders that insist on playing that game it isn't even funny. 98% of the time they wil fade and we'll blow by them 5 miles down the road just holding the same pace.
There is a reason why we caught them in the first place. Same reason I chose not challenge a speed demon that catches me from behind.
This happens so often I decided to make a video of one incident.