There are many ways to get a god neck.
For example inflating only the neck before inflating the whole balloon or inflating the balloon to rated size then sit an bounce carefully on it.
What I do most is pulling the neck out while blowing.
I start with that as soon as the neck begins to stretch.
No matter how impressive necks of "prepared balloons" are, the best necks in my opinion are when "fresh", unused balloons are blown up to their max.
The way these balloons feel (and look) is just awesome...
But I can't do that always myself because very often I just chicken out before balloon and neck are fully inflated and stretched out.
But I am lucky enough to have a good friend who blew several balloons for me to their limits - and beyond