Sorry to disappoint you but particularly counter flashing for masonry chimneys. Counter flashing is designed to be pointed into the mortar of the chimney and ensure a water tight seal of your chimney at roof level.
Sounds easy enough, but this has become a issue between roofers and chimney professionals over how it should be done. In the recent years, roofers no longer point the counter flashing into the mortar and instead attach and seal it over. Does it meet current code? Yes. Will it eventually leak? Very likely. Florida is a very harsh environment for sealant, or any material for that matter, so the typical outcome after a few years is deteriorated sealant and water intrusion into the home.
Above is what I typically see with counter flashing a few years after installation, not good! So the next time you are having your roof replaced I highly recommend having your counter flashing replaced in the traditional fashion, by pointing the flashing 1″ into the mortar. It may cost more but you will thank me in the long run 😀.