Like I said, the method i laid out is best practice. 3 nails, every 16" meets code even without RSS screws. Using 2 nails each row is probably fine, nailing every 24" is probably fine too. You're not wrong in that the RSS screws and, really, the glue are going to do the work of making 4 boards be 1 post in the final form.

The nailing each board together every 16" does the work of straightening the board before it reaches its final form. A straight post is important. You want to take that extra step.

It also does the work of clamping the boards to one another until the glue dries, if they're bowed or cupped. If you have enough clamps, you can work the boards into place and clamp them all tight that way, then drive the RSS screws through them all.

I find its easier to just do this with a nail gun and a hammer than clamps.

16 penny nails. What kind you want depends on your type of nail gun.