Good thread on 2 sided heeling. I find that 2 sided heeling does not really improve marking in any degree but does give me some options for situations to help the dog understand what is going on. Examples
1. keeping control with an especially attractive flyer - allows me to step forward and keep dog focused on other birds
2. Poison birds - heel the dog to the oposite side after the bird goes down.
3. Running blinds behind a gun station, I will run the dog from the side he needs to be on for the gun station
4. Momma Poppa setups, run the dog on the side for the bird being retrieved
5. Breaking birds, I'll run the dog at times from their less comfortable side to make them rely on me more.
Just a few situations I can think of, off the top of my head...