I lube mine up and installed them to finger tight and then back them out around 1/8 turn so the bolts have no preload before I start stretching them. I zero the gauge on every bolt and I do see some small variance (maybe .0007 max in the lengths hence zeroing the Pro Form stretch gauge for each bolt.
I try to split the lengths to try and get them stretch to the middle of the short and long lengths, IE .0057 to .0062 I shoot for .0060
I have swap bolts around from rods to other rods in the same set after measuring them to try and get them matched up to have the same or close to the same lengths on all the rods
I guess you could take all the bolts out and measure them and then install them in the rods to get the lengths close together on each rod Maybe that is being more anal than needed. Your choice