Not totally random, but yeah it's kind of a crap shoot. But to be fair it's no different than a lot of other pharmaceuticals where it's just trial and error until you figure out what works for you.
So like pharmaceuticals, you figure out your goals, go with something in the range that works for most people. It doesn't hurt to start very small (0.25g), which some people do every day. There's a lot of variables including strains and even when/what you ate last, where you are in any kind of hormone swing (men have them too), so trial and error is about as best we can get for now (recreationally). This is why I'm really excited by these new pharmaceuticals.
I heard no such claims, but also he hasn't finished his WWII series yet, so a little premature to dismiss him
Edit: When I said conservatives, I meant conservative values