Flow coat is a term use for usually the second or third coat of clear.
Tack coat than flow coat , It does not mean it will come out flawless even if you have been doing it for 20 years.
But the better you can lay your flow coat down the less you have to sand and buff.
A flow coat in my world is not a second or third coat of clear, it's the second and final application. After clearing the project with 3 or 4 good coats and allowing it to dry, first wet sand the finish (400 or 600P) to be sure it is perfectly smooth and flat, then reapply clear. When you mix the clear for the second round add 30 to 50% more reducer. The added reducer allows the paint to "flow out" more resulting in a very smooth and even finish. Start with a tack coat (not too wet) and allow it to flash. The tack coat will help prevent runs (very important step with the added reducer). Follow the tack coat with 1 or 2 wet coats (let it flash in between) and you're done.
Flow coating works great, but it's not necessary on small parts like a PS3 controller. You should be able to spray a very good finish on a small part like that with the conventional method. Flow coating comes into play on completes or large surfaces.