Initial disclaimer: If you are struggling to find your grandparents or great-grandparents, you may become terminally discouraged reading this post. It is a fact that some genealogists inherit huge files from their relatives. Some have even done all the work themselves. When I say large files, I mean more than 15,000 individuals and more in the neighborhood of 20,000 or more. I realize that some people cannot imagine being related to that many people. Personally, I am convinced that when you get over, say, 10,000 you are probably not related to all the people in your database. But since I fall into the higher end of that category, I thought it necessary to address some of the issues of the larger files.
As a side note, I think I will scream the next time someone asks me "How many names do you have in your file?" Genealogy is not a competition sport. I happen to come from several very large and genealogically active families. You may not. Don't compare totals, it is not productive.
There is really no practical upper limit to how many people you can put into one file. Do the math, you have thousands and thousands of relatives. Just because you aren't acquainted with all those thousands does not mean that they don't exist. Most people focus on their surname line to the exclusion of many collateral lines. For example, you may know your mother's family, but have never met your father's. Another issue is that by and large the children and their spouses of remote ancestors are ignored. I still have many lines that show only one child in a family. This is not only unlikely but misleading. Even if you claim to be from a long line of families with only one child, that is impossible to be the case with each of your ancestors. If all of your ancestors only had one child, you would not be alive today.
Some people find a surname book written by their ancestors and think that all their genealogy is "done." Would you like to bet? Anyway, one book does not a genealogy make, as they say. I happen to have about six or eight of these books and will probably die before I get all of the names verified and transcribed into my own files. By the way, you could put all of the documentation from all eight books on a single sheet of paper and have room left over.
Back to the large file folks. Here are some admissions, which I am assuming are pretty generally applicable to almost everyone with the same type of huge genealogy file. To start out, most of the names have been "copied," that means they were gathered by someone else. Either the names came from existing files or are being transcribed from online or other published sources. I commonly find people claiming to have thousands of names have copied the inhabitants of whole towns and villages. In my case, my Great-grandmother practiced the name extraction method of relationship. She would copy down any person in a certain geographic area with the same surname. I know for a positive fact that these people are not my relatives, but I can't prove that they are and I can't prove that they are not. Since I don't have the luxury of talking to my Great-grandmother, they now reside in my files indefinitely.
One rule that is almost certain is the larger the file, the less proportionate amount of verification of the individuals. I have thousands of names in my file acquired from years of finding family group records and looking at other files, that have not been verified with any sources even though I have spent thirty years doing genealogy. At latest count I have over 70,000 documents, but if I had documentation for 20,000 people, the number would be astronomically larger.
There is a subset of people with huge files. These are the people who have nothing more than a computer file with names. I meet people all the time who have received a file from their relatives with tens of thousands of names and they couldn't tell you their own grandparents' names from memory. Fortunately, I am not in that category but move a few dozen generations back in the past and I am pretty vague about my ancestors without looking at the file. I could belong to dozens of heritage organizations, Suns of the Utah Pioneers, Civil War organizations, Revolutionary War organizations, all sorts of stuff. When you get right down to it, having that many names is an oppressive burden if you are obsessive about documentation.
So what do I do about this huge pile of names. Tune in again for another installment of how to deal with large numbers. On the other hand, if you only have a few names and are struggling to find your family at all, feel lucky, you don't have to worry about what to do next.