Definitely a scattergun approach but that’s similar to how nature does it, I’ve heard the survival rate for seedlings in north American confirer forests to be about 1:1,000,000.

Is that for natural or manual (eg from helicopter) scattering?

Natural. Each year a forest may produce hundreds of millions of seeds but only a few thousand saplings survive.

You do it like this https://youtu.be/VbBDX9ySk60 , 80-90% survival rate is common