Here is a good discussion of factors that influence the accuracy of the position displayed by your device: https://www.gps.gov/systems/gps/performance/accuracy/
There are quite a few items in play, especially since not all GPS receivers are created equal. I have been using GPS for many years, principally to record the location of archaeological sites and it works wonderfully, especially when contrasted with the technology previously used. I have witnessed multi-path errors (signals distorted by canyon walls) so bear in mind that nothing is perfect, even electronics in outer space (heresy to some, I know...).
one or more gifts or other benefits from the co-op.