I suppose in addition to the spreader setting, your walking speed would play into it too. If you walked twice as fast you would have covered twice the area.

Possible that could have an effect, but I'm no lollygagger. I'm 6'6" and take big steps...

And, we're not talking incremental here, the bag is sold as 5000' coverage and the part of the lawn I just fertilized is just about 2000'.

Did you check calibration? I thought there was a line that you check the opening to, not some business with a drill bit.

Yes, ran thru their procedure, which is not at all difficult, and rechecked to be sure. The drill bit test is their method of confirming the adjustment to be correct, and I'm sure the adjustment is per Scott specs.