I save a rod just for break in purposes. Take the new one out, slap in the break in rod and have at it. When you're done breaking in, replace the original (new rod). I use the break in rod for 2- 3 engines- possibly 4 depending on how much fuel it takes to loosen them up.

The top to bottom crank pin measurement will always be smaller after running for a while.... maybe only 0.005 smaller, but thats all it takes. Most good cranks will be 0.196" all around and probably slightly less up and down after running a few gallons- like 0.1955". If you get to 0.195" it's time for a new crank because even a new rod will be loose.

If you don't run the engine too hot, overrev or have a bad break-in (too cold), you should get 2.0gal on a rod. Just inspect frequently

Now, currently I have 2 engines with 1.75gal each on original R5 rods. I will run practice and maybe a heat or two more with each at the WinterNta's before I replace rods.... no matter how they feel/look/measure, etc.... 2.5gal. is my cutoff on a rod.

Avoid cold break-ins to prolong rod life