I would love to be able to run several tanks per modification, but that is not feasible for a couple reasons.
My commute is not that long, I can run a tank of fuel over a 2 week course if I drive it 3-4 days a week. I would be updating once a month if I did this, and the thread, and my personal motivation would die off.
If I was going to put hundred and hundreds of miles between upgrades, I would be doing a dis-service to myself, environment, and the entire principle, by running lots of miles in an in-efficient manner, just to prove the effectiveness of this modification or that one.....
My personal desire to throw all the big/primary/known modifications at the car at one time is too great. I could not bear to only rebuild the carb, and leave the tires low, so I adjusted the tires.
At your suggestion, I am now running almost a full tank of fuel between reports, and noting the modifications for that tank. Some stuff falls in the middle (differential and trans fluid) but I will do my best to enact the modifications at the beginning of the next tank, for reasonably accurate reporting.