If I were to go only by my experiences with my paternal grandmother's family, I would come to the conclusion that it is easy to clean up my direct ancestors on the FamilySearch Family Tree. But I realize that I may have very few relatives on that particular line, so none of them would have created unnecessary duplicates or added incorrect people to the families (although I do need to do a little cleanup on my grandmother's siblings).
Today I'm going to tackle something a bit more challenging: my Irish ancestors through my paternal grandfather, including Smith, Bannon, Hyland, and Reilly. I expect this will be more complicated but more enlightening as to the issues dealing with a collaborative family tree.
My paternal grandfather was William Henry Smith, born 1889 in Newark, New Jersey and died 1961:
At some point, I'll need to add his children other than my father, but I'll leave that for now and focus only on him and his ancestors. I didn't notice any duplicates for him, so I'll keep with the Smith line and move on to his father, Charles Henry Smith, born 1859 in Newark, died 1906.
No problems there, and no obvious duplicates. We move on to his father (my great-great-grandfather), James Smith, born about 1825 in County Cavan, Ireland, died 1872 in Newark.
FamilySearch suggests one possible duplicate, based on an 1871 John Smyth born to a James Smyth and Mary Reilly in Ireland. But since my James Smith left Ireland in 1842 and his last child was born in 1867 in Newark, I have marked the suggested duplicate as not a match.
Finally, James Smith was the son of Philip Smith and Catherine (surname unknown), so I will need to add those to the tree.
And with that, I'm done with the direct Smith ancestral line (I'm sure I'll need to do some checking on the Smith descendants).
I'll save the Bannon, Hyland, and Reilly lines for tomorrow.