Gotta weigh-in.
I think Pete summarized it perfectly in his 9 Sep. post - "It's hard to maintain straightness on a steep hill."
Guys, if you put a 3"-wide painted line along any calibration course, I would venture to bet that none of us can stay on that line the entire 1000 - 2000 feet. The wobble in our ride impacts your counts by 1-3 clicks on each course. I notice this when I ride in the wind, or am just feeling my age. Wobble is there on every ride.
When we get old enough to need training wheels to ride a sufficiently-straight line, we need to hang up our JO. Until then, I intend to accept that my calibrations may yield a difference of up to 5 clicks per mile, and accept a variance of 18" per mile.
I have always had 2 clicks more on my uphill cal rides than my downhill (solid tires, not pneumatic). I expect it. And, if I don't have that variation, I know one of my rides had too much wobble, likely on the uphill rides.
Just my ramblings while the Indians beat the Sox. GO ROCKIES!