At least you can't see their muscle tissue under the scales. 3-4 days in salt should be more than sufficient. Then just regular water changes and they'll heal up in a week or two.
For Senetti, I stopped using salt the 48 hours after she was freed from the decoration. I was more concerned about infection setting in because her wounds were open.
The day Senny got trapped I believe was officially day 8 for salt treatment. I put her in the guppy tank so she could hunt snails and get some exercise. Never thought she would try to swim through that decoration.
When I came home and looked for her, I couldn't find her, then I see her stuck in something at the bottom of the tank. I was so pissed because I thought she drowned, but I noticed her gills were still moving, so I had to pull her out to the top to breathe and propped her up while I gathered tools to free her.
There was more than a few times I noticed little bits of white fungus forming on her wounds, so I put her in a WELL filtered tank with a ton of water movement and that cleared it up in a couple hours.
As for your feeding regimen, I know plenty of betta owners that feed 1-2 pellets 3-4 times a WEEK & the bettas are healthy and several years old.
Keep in mind, if your betta does NOTHING, it's going to get bloated & fat just like any couch potato chip eating human.