Weeks? Sounds like he was trying to align the fence with his neighbor's house instead of the blade. At least your buddy finally got it cutting straight before the wood rotted.
That's the thing though, the fence doesn't cut. The blade cuts. His fence was just finally aligned right to guide the wood into the blade on a straight line. A lot of people mix that up. If his cuts were off before, the fence was out of parallel with the blade. That's always the first thing to check.