I have been very fortunate in that I have found probable families for four "lost" grandmothers. That means several matches to the same surname family. I am still sifting through the poorly documented trees and old documents trying to find actual parents but it is much more than I had before. That being said, the families are all Colonial America and that is where I am finding most of my matches.
And one of the reasons I have a big tree is because so often it is the uncle's cousin who writes the little genealogy booklet that lists my ancestors information.
I have noticed that many so called genealogy DNA experts know gobs about STRs and haplogroups and very little about recent (last 400-500 years) family history research.
One of the tricks I use is to look for quirky spellings and surnames of unconfirmed lines in the long name list. That has proven useful for me.