When I was asked the prove the true parents of American Naval hero Reuben James, born in Delaware, I read every land record in Delaware, for the surname James, beginning in 1766, ten years before he was born until 1838 when he died. I indexed by year, name of purchaser, and witnesses, since witnesses back then were usually relatives and assembled a chain of James men, related to each other when the records said, to my nephew, to my son-in-law, etc. I cross-referenced those names with the available wills. I proved his parents were REUBEN James and Mary Hitchens, proved his siblings and eventually found his grandfather Daniel James.
In many ancestry trees and geni dot coms, he is given a father named John .To insure no one would dispute my findings, I proved to the satisfaction of the project leader that John died before REUBEN James was born. The total number of land records and wills I examined - 311. Needed a lot of coffee. And aspirin for the eyestrain headache. Took a week of digging, about 6 hours a day