Do surveyors sometimes disagree on boundary locations?

First, it is true that surveying is an exact science in certain ways. For example, surveyors don't disagree significantly about the measurements of distances or angles, a mile is a mile, and 90 degrees is 90 degrees. But in other senses, surveying is relegated to some uncertainty, usually stemming from conflicting evidence which often causes differences of opinion. The maps that surveyors are required to record on behalf of the public are intended to disclose uncertainties. The mere fact that surveyors publish their maps for other surveyors to see and review has greatly reduced the number of cases of disagreement over time, mostly since 1980. But property rights are at issue as well and a surveyor is obligated to review any evidence that may be discovered that is contrary. It can be uncomfortable being involved in such disagreements, but ultimately once the conflicts are resolved they should not need to be visited again.