I was doing one plant per in 5 gallon fabric pots when I first started and I might go back to that now I know what I'm doing, but I'm trying to mimic the ground as much as I can and the huge pot thing has been working for me
That looks like a 50 gallon pot in a 3x3. With smaller pots you don’t do multiple plants since the roots will compete with each other. In this scenario there is ample room for multiple roots and companion crops can provide synergy between plants. Clover returns nitrogen to the soil for example.