as always its the owner which needs the training! Ah but unless anyone tells you you won't know :D I didn't know that the behaviour had to be proofed elsewhere until it was explained to me :)
I usually wait until near the end of a walk before I do any training. By that time he has had loads of running around, has explored all the undergrowth, sorted out a few squirrels, and has swum in every available water source and is thus in a more receptive mood. :) I don't do much just a few sit and waits , the odd down stay where I walk away and come back to him and walking to heel off lead. The reward for all these is to go and have some more fun. Harley's walks are nearly all off lead so sometimes I will put him back on his lead part way through a walk for forty or so paces and then let him off lead again. Again the reward is to go off having fun again.
By doing just a few minutes of training on each walk he soon realised that he was required to do as asked wherever we were and not just at classes or at home. I never do anything but a basic sit and wait before exiting the car and sitting and waiting to be released from the lead at the beginning of a walk because it would probably be asking the impossible at this stage and was advised that you should always set your dog up to succeed - if you don't think he is going to come back when you call him then don't recall at that point or he just learns that he can ignore you totally or that he only comes back after the second, third or fourth recall command.
I also hide a lot from him so he has learnt to keep an eye out for me and now checks regularly that I am still in sight. It has helped with his recall tremendously :)