There are certain times when one does not have that option. There are also times when one might not have noticed. I know that has happened to me on at least one occasion that I am aware of. If I do not notice the signage when entering, and I have a need to enter, I will be entering. If I am CC, no one will know, so it really does not matter, as long as it is not a state of federal carrying violation in known “GFZ” places, such as court buildings, schools and post offices and their property.
I live near a school that is a “drug-free” zone. One day, many years ago, while nearing my home, I saw a police officer in my yard with a neighbor. The neighbor’s fence was knocked down, and there were two sets of tire tracks from my driveway through his fence. A small scale was found in the grass near the tire tracks. The officer stated it was one typically used in illegal drug sales. How could that be? It is a “drug-free” zone. So, yes, I will carry, unless it is a carry violation.