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I was thinking a bit more about this and my theory is something like this:
If the mount is a "dumb" manual or motor drive, the movements are relative to where the polar axis is pointing and so alignment is more critical. If you are say 5 degrees off, your movements will pivot about this point rather than the pole and so the larger the arc you move around, the further out you will be.
If it is a GoTo type mount, probably any manufacturer and not just Celestron, maybe the computer is able to "skew" the stars around inside its little brain. Thus the lack of alignment is compensated to some extent. However, as it tracks an object, is still only moves ONE axis. This will cause the object to slowly drift out of the centre with time - this happens if I center a star and leave it for a while. The star is no longer in the middle after a few minutes (this is basically what the "drift" method uses to get proper alignment). You will notice that when you press the final align button, the hand control has a bit of a think and then says alignment successful.
Don't know how much of this is actually true, but maybe this helps to explain why some times have have taken almost no care in setting it up, and yet the slew is still pretty close...objects are at least in the finder, but not quite in the eyepiece. My job is a computer programmer, and I can see that such compensation could be possible...actually they say alignment of an Alt/Az type mount is less critical than an equatorial because it moves in two axis to track something...but you will get field rotation near the pole.
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