Yes, public shame works, because it sends a message to the offender and to future offenders that their behavior is unacceptable. Public shame makes people think twice before they act. If some is embarrassed about their actions, they will be less likely to do a certain thing in the future. Public shame is an effective control tactic.
Yes, I agree that sometimes public shame works. For example, I have heard of people who have committed crimes and have been ordered by a judge to stand outside the store they stole from wearing a sign that said something like "I stole from this store." Obviously, the person who had to do that felt shame and probably thought twice about stealing again. In other cases, I don't think public shame works, and I think we must balance carefully the effectiveness of it and the impact on the individual as public shame can be mentally, emotionally, and psychologically damaging.