I p&g at moderate speed on freeway perhaps 68 down to 61 or therebouts.
A truck zoomed past the other day and sliced into my lane doubling my disengagement for easy 11 seconds.
Ive since found latching my p&g to semi or bigger pickup or hauled trailers drafting provides much better returns.
The smaller vehicles are much harder to do this with and require much higher frequency of gear engagements but can also be done well enough.
My semi slip stream zone is variable from a close of 2 car lengths to as far as 13 before re engaging.
I still get some draft benefit that far out and its not so busy in and outa gears. What I really like is to time the gentle hills and key off on the really long glides.
Just wanted to share this as everyone coming here new is looking for that amazing return on mileage thier first try this might help them see solid mpg gains.