coal use

It is interesting see the difference in coal consumption for different users of the same equipment. Seeing a variance of
20-30lbs a day, for the same equipment with different users. Not really scientific as there are variables, but even so.
Says a lot about set-ups and tuning.

More to do with variances on the house, square footage, insulation, windows, kids going in and out the door....

I agree, but the biggest variable, is the measure of " maximum ". Same equipment running at full tilt should be close to the
same. It is not. A full grate is a full grate. Maximum feed is maximum feed regardless of what is going on in the house.
Coal quality is a huge variable as well.

Where are you getting data showing that folks are running at maximum for an extended length of time?

FYI, I have NEVER run over half output (1/2 scale), ever.

I believe the setup has much more to do with coal consumption than tuning the stove. Setup includes stove location, house size, home insulation, chimney height,coal trol location, coal trol temp setpoints and other factors. If by tuning the stove you mean using a draft gage to set the correct draft then I doubt that this is as critical as the aforementioned setup factors. I choose not to attempt to use a draft gauge to set up the proper draft. I just properly installed a Fields baro and set it to Larrys recommended approximate setting. Made sure the stove pumps out good heat and that exhaust stovepipes were not getting to hot to the touch under various outside weather/wind conditions.
A lot of folks on the forum make a big deal out of setting up the perfect draft for best stove efficiency and I think that could be a very elusive target. To many variables are involved. Do you set the perfect draft for a calm day or a 10mph wind day or a 15 mph wind day or for some other weather conditions? If you monitor the draft what do you do when it's not reading the perfect setting?
Remeber the old saying , "if it aint broke don'fix it".
P.S. I heat a 2000 sq ft tri level and am burning 40days per ton thru Nov , Dec ,Jan months. Looks like I will burn3 & 1/2 tons or so per year. Hearth model on 2nd level , coal trol set at 72 degrees and bedrooms & living space plenty warm.