A lot of yacht people have recorded their track (waypoints) through areas where there are known errors
It would be advised that before you rely on any "way points" you get from others that you be sure of the map base coordinate system they used to collect them. You also risk transcription errors on either their end or yours. It just underlines that you never can escape the fact that information like this is never 100% accurate.
Now consider a chart created from many sources. You have a GPS
with WASS accurate reception
but a chart that is not as accurate as you instrument. Your additional GPS
accuracy is worthless without a matching chart just as accurate. The navigational error is the error of the both added together.
Acquired GPS points might be 100 yards off from your current
position and you could never know. You double the GPS error when you attempt to hit a recorded location with your GPS since the time of collection was not the time you arrived. You never can know how accurate the data was nor how different your receiver is at that time.
From a navigation
perspective 100 yards is pretty darn close when coming 5,000 miles away. You would clearly jump for joy extolling how you were perfectly accurate with your arrival. From a piloting perspective a coral head
is too close to trust a GPS point. The context of how you apply information has different meanings. Nothing illustrates the point better than GPS navigation