Im not currently in the diving industry. But, i have some good friends who do it for a living and i am pursuing an interest in it as you are.
Based on feedback from my friends and other bulletin boards it seems in the fort lauderdale area there are so many dive masters and instructors that many schools have a rotation list. So you may get 3 classes a month to teach or no classes for a few months.
The overall thing to consider, at least wherei am, is that there are so many open water instructors down here that they tend to take on the duties that divemasters usually take on in other parts of the country. So i find a dive master cert is pretty much useless down here for employment unless you know the owner of the dive business.
Many of the instructors i have met do it seasonally or part time.
Many will bartend during the diving off season (when tourism is booming in fort lauderdal and the bar business is crazy) then teach scuba or work on a dive chart in the dive season (when seasonal divers go back into diving and the bar business is slow).
My friends make around $60k a year but diving amounts to about $17k of that with the rest in the bartending business.
The last thing to realize is the competitiveness down here. Again down here open water instructors are as common as dive masters elsewhere in the US.
So to stand out from the rest and secure better employment options instructors need to achieve higher cert standards. So its common for instructors down here to be instructors in several dive organizations. Some of the more prosperious schools have instructors who are instructor trainers in with several dive organizations.
Now if you happen to be own of those multiple agency instructor trainers and own your own dive operation then you could make some very good money.
Again im not in the profession. But, try visiting a few dozen shops around here and you will see many of these store owners drive lexus or BMW's or Jaguars etc.
Leads me to believe they are bringing in some sort of reasonable money from their dive business!
As a good supporting example to this i saw this past weekend a small dive operation for sale in key largo for $1.2million dollars. Now if you can own a business like that for diving then you gotta be making some good reoccuring revenue.