I have hunted a yard, of a house built in the mid 1950s, and found well over 100 coins. (Obviously a house occupied by a rambumcuous bunch of kids sometime back in the 1960s or whatever). And then I have hunted house yards that date to the turn of the century, and found perhaps 3 coins. In these example cases, I knew for various reasons, as you specify, they had "never been hunted before". And in each case, were undisturbed (not re-turfed, not filled, etc....) So your question is just impossible to answer. It depends on the type people who lived there. Some type people just don't "lounge and play" on their yards. Others do.