If I don't especially like an FA flavor at 5% or less, I've never found one that improves with more. Some seem to have a double peak, where they taste their best at maybe 3%, fade or taste bad until 10%, taste okay again much higher. I get much better results with the lower peak. Cocoa is one of those; I think Halo's Belgian Cocoa is based on the "higher peak" of FA Cocoa.
In recipes I sometimes use as much as 6% FA flavor, but I've found even those benefit from dilution down to 3-5%. Most FA Tobaccos, way way less for me - over 2% and my head would explode, either single flavors or mixed. Their RY4 is the only one I can use higher. Dark Vapure of course, ideal at 0%. lol!