South Florida is a brutal place for a coating. The UV load is high enough to break down binders on a south or west wall years before the same product would fail in a milder climate. Summer rain finds every unsealed crack and gets behind the film. And constant humidity means mildew doesn't just land on the surface — it establishes in it.
When a repaint fails early, the cause is almost always one of four things, and none of them is the paint itself. The surface wasn't washed, so the new coat bonded to chalk and dirt instead of stucco. The mildew was rinsed rather than killed, so it grew back under the film. Stucco cracks were painted over instead of patched, so water kept getting behind the wall. Or the caulk at the windows and door frames was left to fail on its own schedule.
Proper prep takes longer than painting does, which is exactly why it gets cut from cheap quotes. A real exterior scope should list, separately and visibly, the pressure wash, the mildew treatment, the stucco crack repair, the re-caulking at every joint and penetration, and spot priming on every bare or repaired area. If those lines aren't in your estimate, they aren't in the price, and you'll see the difference in year three.
The product matters too, but less than people assume. Elastomeric coatings bridge hairline stucco cracks and handle movement well; premium acrylics breathe better and are usually the right call where moisture needs a path out. The wrong choice for your wall will fail no matter how good the brand is — which is a judgement call your contractor should be making on site, not from a price sheet.
One practical test when you're comparing exterior quotes: ask each contractor what they'll do about the mildew on the north wall. The answer tells you almost everything. 'We'll pressure wash it' is a different job than 'we'll treat it, let the solution dwell, then rinse,' and only one of those stops it coming back.