When water conflicts with land, land will win every time without a trained response. Most of the land drills are very easily understood, and everyone for the most part can walk on land, chew gum and walk well? Water is a very different concept for dogs to grasp , a dog can run much faster then it can swim. The swim-by is a water drill. I have had dogs that never completed the swim-by, and had to go to creative drills. I know Mike has too. Quick learners are the most difficult, they learn the concept, sometimes in a day or so, pressure is applied and theydon't know how to get out of the pressure. Water comes in conflict with land and some trainers start digging a hole. If you are not a force trainer, or you don't use a e- collar I think you probably have to be very creative in your approach to the swim-by. Most experienced trainers, pros included, sometimes do the swim-by with disciplined casting the entire competitive life Of the dog. I know I use it many times over the years with some dogs. You won't see some of this discussed in DVD's or reading material you learn it through experience. Many new trainers try to think like dogs, use human reasoning, to find out the why's of the dogs not responding to training. Paraphrase Mike Lardy, I don't why this works, but it works and I am not training lab rats or ringing bells so really doesn't matter , it works. Perhaps the OP answered her own question, water Tee or Swim-by, I don't train with pressure?