I did a bit of testing and found something strange. If all 12 lasers is staked 3x4 they all fire, but if you make them 2x6 only 8-10 work. My two sets of six only six work. I think we have a game bug here that is caused by the area the guns are spread.
This is a hardcoded limitation imposed by Eleon and they are the only ones that can change how it works. I doubt they will be changing this any time soon if ever at all.
The way Eleon is slowing down tools and weapons lately and imposing hard caps across the board we are more likely to see this number reduced in the future rather than increased.