Training with treats is very effective during the 'learning' phase of training.
While some dogs need only our approval or a pat on the side as a reward for good behavior, others need a little more incentive to respond consistently to our commands.
Treats are an excellent way to reinforce desired behavior if they are used correctly.
To keep pets from becoming dependent on treats for behavior that is expected of them, we recommend limiting treat-giving to the learning phase of training. When teaching the 'Down' command, for instance, place the treat by your dog's nose and slowly lower it to the floor while you give the 'Down' command verbally. When she lies down, reward her with the treat. Repeat until you are confident she understands what behavior is expected when you issue the 'Down' command.
As you advance into the testing phase, replace the treat with verbal praise and patting. The goal during this phase is to have her respond to your command in order to receive praise. The best way to use treats during this period is intermittently. She'll never know when performing the command will bring her a tasty snack, so it keeps her interest (and hopes) up. This intermittent positive reinforcement is a great training aid. Liken it to people playing the lottery - they'll keep playing on the outside chance they will win big. The same goes for your dog.
The only time I recommend consistently using a treat throughout training is for the 'COME' command. This is the most difficult command to teach and you may need every tool in your toolbox to get your dog to respond consistently. You have to make your dog want to come to you, and a treat - together with praise - is often the reason she will choose you over the many other temptations that are 'out there.'