Just the Tampa newspaper archive search mentions going through over 200 cases. As badly as this law is applied in some of the cases, who knows? Quite possibly. It is estimated in the article, that by polling several country and district prosecutor's offices, that the law is cited in hundreds of assault, manslaughter, and murder cases each year throughout the state.
I absolutely agree that the fact Zimmerman ignored the Sanford officer's assertion to stop following should be what the jury focus on, but, you will see some cases listed where the SYG citing defendants actively pursued victims, assaulted victims who were incapacitated, and even shot or stabbed victims in the side or back of their bodies, as the victims turned to retreat. Many, many victims were unarmed, and still some of the armed defendants won their freedom. The key to that inanity is that the law "does not require retreat" being interpreted to also not exclude pursuit. SYG is also applicable to a bystander, not under threat of harm themselves, to go over and intervene with an altercation or what they believe to be a felony crime in progress.