Brent,
Your point seems to be in conflict with the DOP definition in the link Zspectre provided in his post.
2.Look at your satellite screen and see how many sats. you are getting and are they over head or horizon oriented.
Horizon oriented sats. give much less accuracy than overhead sats. And remember you need a minimum of 3 but 5-7 with 3 overhead is premium.
Then again your point seems like it could be verified in the "Atmospheric Conditions" Definition from the same link.
What I did get out of that link is errors do happen, but those for the most part result in football fields size errors.
I did have a 300 mile mistake on my old 45XL years ago. I caught it and recognized the magnitude of the error and marked it before my unit reset itself and stared a search the sky function. When i e-mailed Garmin they were puzzled and stated that the military didn't give them any warning about adjustments or testing the civilian signal. Had I not been watching it happen I wouldn't have had time to mark the location that came up on my unit.
I also had my old unit loose everything while duck hunting on a very large lake. All the markers(buoys) were pulled for freeze up but I had them all in my unit.
I had to send it back in and it was replaced for $68.00. small price compared to the $350.00 or so I paid for it.
I also lost all data with that old unit when the buttons were pressed in the right way in my pack. They (Garmin) confirmed this when I contacted them.
This is done on the old ones by holding down one button like page(might be wrong on this, but one button would clear all waypoints and another button would clear all data like satellites and everything) and holding it while powering it up.
The new units do not have those old reboot feature, Thankfully.