Phase 2 training is where you formally teach the scientific concepts of discipline to the dog.
Therefore, you will teach the dog that there will be an aversive correction for disobedient behavior, and more importantly how to rectify himself if corrected and avoid corrections altogether.
Physical corrections in phase 2 are always the minimal amount that is recognized as uncomfortable to the dog. Basically, just enough to teach the dog about corrections, but never enough to cause fearful or painful responses.
Do not attempt to use phase 2 techniques unless you have completed the corresponding command in phase 1 or you will make the training process more stressful than necessary, cause side effects, and ultimately take longer to reach the results needed to move forward. The dog must understand the meaning of the command first and why it is GOOD to obey before teaching discipline. Proper completion of phase 1 will also raise the reliability of the dog's obedience when combined with this phase.
Since phase 2 only uses the mildest forms of physical correction, you can expect much improvement in this stage, but still limited obedience in situations with moderate to high distractions. In these cases it will be "worth it" for the dog to receive mild discipline in exchange for attempts to engage in certain desired activities.
Also, phase 2 is limited only to "on-leash" discipline.
To teach discipline around high level distractions and when there is no leash attached you must complete the requirements of this phase and move to phase 3.