25 yards ahead for upland game is about right. Our English Springers did this automatically, quartering back and forth. I am told a lab can be taught this, while spaniels do it out of instinct. Too, most delightful, is the jumping (springing) when in tall grass or weeds. Most field dogs have a slightly longer tail cut than bench-trial dogs. This 'flag' is held aloft for you to see locate them.
: When retrieving, it didn't matter how far away the birds fell - strong and resilient dogs for their size.