Florida Metal Roof over Existing Layer of shingles

When someone has a metal roof installed over an existing layer of shingles in Florida are the decking boards Re-secured?
I know when a roof replacement is done with shingles the contractor has to show that the decking boards have been Re secured with 8D nails with min 6” spacing…is it the same when having a metal roof installed over shingles?

All re-roofs need to be re-nailed as indicated in the FBC.

If the existing sheathing has already been properly nail originally. Then there’s no problem with it.
As a matter of fact. I’m having this done next October. To my own home.
I’m a Florida license residential contractor. And I’m sure that don’t mean anything to anyone. But when I had the crew nailing the sheathing on. Everything was at 4 in on Center and in the field and on the edges

I installed about a hundred metal roofs in my time. I have never installed the panels directly over a shingle roof. We always nail 2x4’s or 1x4’s horizontal every 2 feet up the roof, this is what the metal roof will attach to. not through the old decking or shingles.
nailing on the nailers with 3 1/2" exterior framing nails through the shingles and into the existing rafters.
We will usually also use nailers on a new roof as well. as plywood makes the roof panels kinda wavy. and lay weird. having nailers only where the screws will be makes for a better metal roof install.