Many SEOs don’t really trust the Site:URL command. Most SEOs also don’t trust the “About X results” numbers that appear when you make a Google search. I didn’t either, and had always thought that they must be pulled out of the air, and pretty much useless.
Have you ever scrolled to the end of the results to see how closely the numbers match up? For example:
We know that Moz has more than 700 pages in the index (anyone from Moz, please comment your business critical WMT numbers below), and that the number is probably some way closer to 226,000 than it is to 700.