Have been following this thread with interest
There's been some fantastic advice, and as others have said, if you follow Mark's advice to the letter you won't go wrong
But I KNOW how hard it is to be totally consistent, 100% of the time and to be abe to organise your life around what is quite a strict trainingplan. I have gotten to the stage with Chloe where I know my limitations, and hers......so we have a situation where her recall is virtually spot on..............EXCEPT...when she smells deer or sheep
. Yesterday, we were walking in the forest, doing retrieves, and her attention was focussed on me 100%. I was at that stage where I honestly was the most interesting thing at that time. However, after a couple of miles, she suddenly dropped the ball whilst on her way back to me...and charged off...nose to the ground...going from side to side of the path. Sure enough, we both spotted a deer about 100 metres away at the same time. I gave one blast on the whistle, but didn't work. She was offski!!!!! So, no point in whistling or calling her back then...I just let her go and she returned after about 3 minutes. With sheep, well, I just don't let her off lead near them, as I have yet to be able to call her off them. Maybe one day, but certainly not at the moment.
Not sure if this is of any interest or help, but anyway, I wish you the best of luck....and fwiw...I reward Chloe for coming back ALWAYS....even if she wonders back of her own accord. Even the slightest teensy treat, or play with a ball, or a big fuss
It mostly works for us