One very big problem that I think most Family Historians come up against is when particular christian names within any one family are repeated over and over again.
This makes it very difficult to actually separate people into families because these names were perhaps used for a son, then he would name his son the same name, perhaps a brother would name his child with the same name and so on.
Sometimes these same names would pop up in a different geographic location, not that far from where you are researching and that makes it very difficult to decide if this person is the one you are looking for. Did they move away?
People tended to name their children after their parents and/or grandparents. Sometimes if it was a boy they would give him his Mother’s maiden name as a middle name or even his Grandmother’s maiden name. This at least helped to group children into the correct family. Surnames being different you wouldn’t have the problem that you had with repeat christian names.
I think also christian names were often reflecting just who was on the throne at the time of birth. People did tend to use the names of their kings and queens possibly as a mark of respect, who knows!
Hence in the time of William and Mary there would be a rash of Williams and Marys and in Elizabeth I time there were plenty of Elizabeths around.
I have one male family middle name passed down through my ancestors for 250-300 years and this name was originally the name of landed gentry in the county in England where a lot of my ancestors came from. I have never been able to discover just why this name was adopted as a christian name.
One Archivist suggested to me that perhaps a person of this county family had sponsored a child of one of my ancestors and it was a mark of respect to adopt the surname as a middle name. I have never been able to prove or disprove this because it was in the 1700’s
I don’t suppose I shall ever know the truth of this matter.