I picked a number in the middle. And 100 generations would follow my hypothetical fellow.
Either way, it’s a long, long time, not least considering that most people alive today never get to meet even their great-grandparents, which is only three generations ago. Most people know who at least one of their parents is, and have some idea about both; and if they can talk with at least one, they learn about their grandparents. And if they are able to talk to their grandparents, by the same-boat model, they can learn at least something about their great-great-grandparents. But the oral tradition both is and is not durable, precisely because discontinuities are so frequent, and accuracy and honesty aren’t particularly valued. :’)