On the Ram, the exhaust brake has two modes. I use the auto mode all the time and full EB if in varying speed traffic, rolling hills or mountain passes. The difference between the two modes is that auto mode does not engage until you touch the brakes which allows you coast when you let off the throttle.
I use the tow/haul mode any time I have more than 3000 lbs of trailer or cargo (which is most of the time). This is an arbitrary weight I chose since trailers in my state under this weight do not require their own brakes.
The only exception to the above is in slick conditions where I will turn off the EB and tow/haul to allow for smoother power delivery to the wheels without any sudden or quick changes.