What method do you use?
I was going to use a torque adapter on the bolt and then set up the gauge with the rods installed. Preload each bolt then tighten each bolt on one pull.
Seems most people measure the stretch by finding the correct torque required and recording it.Then install the rods and torque.

First time measuring stretch instead of just torquing them.

I bought a rod bolt stretch gauge years ago, I use it all the time now Some of the higher end custom ARP rod bolts will vary some, from 5 to 25 Lbs. between the bolts to get the same stretch
I haven't seen that with the standard ARP 8740 or ARP 2000 rod bolts yet though
Make sure it will measure in 1/10 of a thousands, not in .0005 or .0010

Measuring the stretch by measuring the length is a pain, because if you don't hit it right on one pull, you are supposed to loosen it and start over.

Using a torque angle gauge is easier, and produces consistent results because you can see where you are with it and stop in just the right spot on 1 pull. You probably don't have to, but I'm anal enuff about my motor building to double check the length after I tighten it with the angle gauge. 90% of the time, it is dead on.

Also, put feeler gauges tight in between the rods when torquing take the twisting force off the bearings.

I've found the torque to get acurate stretch varies a fair amount. Many times some take more to get to the correct stretch.
Doug

Just me but I would not torque one side entirely then the other. I have the Lunati gauge. I still go up in steps checking stretch as I go. I will also say that it always takes more torque than printed to get in the acceptable stretch range ( at least with the tools I have).

I check all my rods for stretch in a rod vise first and write the torque needed to get them the middle of the desired lengths I don't do multiple step torques unless I think the bolts are not going to be equal in quality, and then start out lower than what the sheets call for
The two sets of bolts that I had stretch at different torques where in a set of Oliver billet rods and in a set of Molnar

If you torque in steps, never start the final step at anything over 50 foot pounds.Due to friction and stress on the threads at that level, breaking the bolt threads loose from the rod threads,the rotation of the threads will lag behind the rotation of the head. This can lead to twist fracturing of the bolt.

The torque and angle method does seems to be a bit easier. The instructions from Molnar say 30ft-lbs and 60Deg. Then I would measure. Angle gauge cost the same as a torque adapter.

I guess no one uses the torque adapter method because it is hard to setup the gauge to get accurate readings while tightening the bolts on the engine?

Also should you cycle the bolts a few times before measuring?

Rod bolts are stretched to about 2/3 to 3/4 of thier max strength so they have some strtch left before failure whehen running.
So all i do is clean everything well, use plenty of ARP lube, torque to the recomended length, done. What you are doing is just like streching a spring. You can go a certain amount, and never hurt the spring, but if it isn't enough the rod caps may bounce. Over stretch them too much, and with enough load they will fail. The stretch amount given for the bolt you have is right where it will do its best. My rods have a .0004 window i need to be in.