Screws - Adding Additional Screws
When I build a project at my house, I tend to over-achieve and do a little extra, especially when it is labor related or at a nominal cost.
Adding a 3rd screw to a 4" or 6" board at the butt ends or at splices is good insurance. Plugging the ledger board and end joist every 12" instead of 16 or 24" is the same. It takes time, very little money and makes sense. The bracket to joist screws are already spaced about 2" apart, and there would be no practical point to install a screw in every available hole, 22 in all.