Well I figure I'd post here on what we were talking about previously.
SBD is not tied to specific tail types at all and in fact many Double Tail bettas are unaffected by their natural deformity (twin lobes is a deformity that we keep breeding). The only reason that some Doubles are affected is because their bodies are inherently shorter which theoretically squishes the organs together causing the swim bladder to be shortened or pushed against wrongly when the fish eats; this can cause issues with the swim bladder but in no way is it Swim Bladder DISEASE, just swim bladder issues.
Like humans, not all fish have the same anatomy and even a double tail who has a longer body can sometimes have issues with constipation which can therefore create some issues with the swim bladder if their GI tract is constantly swollen with a food blockage. And then you could have a DT with a shorter body who would look like he should have problems but he doesn't; it's all about the genes and how well they are taken care of as well as which foods they are eating.
Swim Bladder DISEASE is an illness, an infection of the swim bladder which can cause anything form sinking (swim bladder can no longer keep air and fills with fluids) to floating (cannot release excess air) along with twirling or rolling. Infections should be treated with antibiotics and generally come on quickly whereas swim bladder ISSUES tend to be life long.
Anyway, back on topic; I don't count my pellets but rather feed m fish until their tummies are expanded and round. Not terribly fat but just full looking. Yes, their stomachs are the size of their eyes but all stomachs are made to expand. I only feed my fish once a day for the adults (babies get twice since they need more), if you want to feed twice a day that is also fine. Also you will know when your fish is getting full, generally he will no longer be eating enthusiastically but that doesn't ring true with all fish of course; each has their own personalities and you'll just have to observe them over time! ^_^