how is it done at the assembly plant? I know its not done by humans and the robots use some kind of measurement or reference.

I'm not tired of it at all. Been adjusting lash with hydraulic cams for over 25
years the exact same way. Never had a problem, ever. Never had a polylock
come loose, never had trouble finding zero lash, and have always done it the
cold method (Shoebox Methods 1 & 2) with the engine off.

Granted, the first few times I had help and direction, but once you get the
feel of spinning the pushrod, the rest is a piece of cake. As said previously
it's about patience. Take your time, have the engine in the correct position,
and just feel it.

With polylocks, you have to tighten both the nut and the set screw together
to get that final bite. I try to go at least 1/16 of a turn after it's tight. Some
do it by torque, but I just go by the feel. You will not hurt a polylock with
25 foot pounds on it. With a short box wrench this is about as hard as you
can pull on it. If the wrench is 6" long you have to put 50# pull on it to get
25 ft-lbs of torque.

I'm changing my valvesprings tomorrow and will be going through this same
procedure once again. Most hydraulic lifters are very forgiving. The general
consensus is that the Comp Rs are not, but I have not found this to be true.
I'll set them to 1/8 turn with 7/16 studs like the last time. I am almost tempted
to go 1/4 turn just to find out if all the bad press is true.