WR, take a look at the location of the signs the next time you are taxiing at JFK. They are not near the taxiway boundary, but rather off in the weeds. I have a photo of the sign and its location, but I do not see a method to upload that onto this site.
I can only say that their location is not within my normal scan. Remember, you are navigating a narrowing strip of concrete that requires careful attention.
Ask around and see how many of your peers are aware of the signs. I did...