Accuracy of VOT: For calibration or just testing?

For my last VOR check I happened to be on a field with a VOT, so I used
that rather than comparing the two NAVs against each other as I had been
doing.  They matched, which I expected, but they were both 1 dot out,
which I did not expect.

Is a VOT the final word in VOR testing accuracy?  I've made several
off-airport-VOR approaches and ended up right where I'm supposed to be,
but doing the math I see that 2 degrees is only about 2000' at 11nm,
so maybe I wouldn't have noticed.

-- 
Ben Jackson
<[EMAIL PROTECTED]>
http://www.ben.com/