I have read hundreds of plugs, used to change them for every race weekend, sometimes during a weekend...but that was back in when changing jets and tweaking the timing, long long time ago, VERY OLD SCHOOL analysis
As for indexing, I think of things this way. We have a very sophisticated ECU controlling an engine designed for max power per amount of fuel used, the more even everything is, including how the plugs are aligned, just makes sense that it work better logically.
Balance is the key aspect of everything, period. The more balanced we can make things the better it will perform so taking the time to index the plugs, though not going to be an absolutely perfect solution unless you have the tools to verify the air flow in each cylinder around the plugs and the effects on the flame front, detonation....it is still a step in the right direction. If we can balance the load on each cylinder just a bit, think of long term wear and tear let alone a bit more efficiency.
I have already seen #1 cyl timing improve by changing out the plug to one that was indexed like the rest, if this lets me run more timing overall, then more power, overall.
After dozens of runs the 91 tune is close to as good as it will be here at 5200 ft with my specific mods.
Once the Torco tune is done I will then get the car on a dyno and post the results and may post the log files as well but not until then.
Some VTC work is one of the next steps to see about bringing in more bottom end which will effect both tunes.
It is not something I am keeping a secret, just something I will do when I get to it and things are done
Lot's of adages can be applied to getting the most out of anything like "the devil is in the details"