Bet its recalls.

I tried a Flexi for long-line recalls ONCE. It wasn't pretty.

As puppies if you guide the dog into the behavior and mark, it goes really smooth. The beginning recall is actually a good example Meridith, the pup is sniffing around and you call him and get his attention at the same time as you guide him towards you with the flexi, then reward, gets super results and sets the foundation up.

A flexi was used on this pup and by 4.5 months old this is how KC was , he knew what the commands were http://www.youtube.com/watch?v=2K-JGufWHYY

That makes total sense since the flexi will usually guide the dog straight back. I have one question about it, though. Have you ever run into a problem when it comes to the dog looking for leash pressure as part of the cue?

I have recently noticed that sometimes without light leash pressure) or a physical signal my dog doesn't know what the heck I'm talking about. She is VERY sensitive to physical cues, intentionally taught or not.

(The kind of leash pressure that I'm talking about is the kind you don't even intend, little arm flexes and stuff.)

For her its to the point that if I accidently say one command while my body is very subtly signaling for another (usually because I'm thinking of the next command) she follows what my body is saying rather than the verbal cue.

I realized this one time recently when I asked for a sit and she downed, I gently touched her collar and she popped back up into a sit!

We have flexis for one thing. Running the unreliable dogs in the rain....stand on the stoop under the eaves- staying dry, let the dog out to go hurry and get wet and still have good control. Honestly right now the dogs are all good enough with recalls that we only use them if we suspect vermin or strange dogs loose somewhere close. IE smell a skunk.

One of the first things I always teach puppies (or new adult dogs) is a solid recall. I hate dogs that run off. I grew up with one that would bolt out the door and tour the neighborhood til we (kids) cornered him and dragged him home as he snarled like he was gonna eat us. (GSD mix that was a wonderful dog given my dads lack of discipline. ) Our dogs wait at the door and are released to go outside by name. It isn't perfect but neither is every family member implementing it. But I will say most people are impressed. Same people that are amazed that the dogs DON'T run off or leave the yard.
My second hate is dogs that "walk by braille"....leash pressure. So the recall is only trained PR and off leash inside a fence at first.