I put the first part of the fence in the same place as the old one was. Staying in about 6 to 12" may have been the smarter way to go just to be safe. I don't have the survey pegs to reference, so I am guessing that the original fence was on the property line.
That is a dangerous "guess".
I've a house on about a half acre in Alexandria, VA.
The land is valued at about $8 to $10 per SQUARE FOOT.
I've had it since 1978 and didn't get it surveyed UNTIL:
A house "flipper" bought the adjoining residence in 2013 and wanted to widen the driveway and put in a nice 2 car garage in the back and a classy wrought iron fence down the side property line.
He thought he would have room for a decent driveway.
In the picture:
on the right you can see his house.
Then the driveway, and grass. In the grass, back near the top of the picture you can see a small wood structure which is an old well cover. The neighbor was under the impression he owned up to the well cover. That about matched where the right edge of the driveway apron joins the street, which is not in the picture because I was standing on it.
So I got my lot surveyed. As annotated in the picture the actual corner is about 6 to 8 inches to the left of where the county put the driveway apron corner.
The neighbor got it resurveyed by a different company and that survey agreed.
The "flipper" gave up on widening the driveway, and the fence, since it would have to be inside the driveway apron.
I had stood to lose a strip about 2' wide if he had put in the fence where he wanted to. Since my lot is about 240' deep that's about $4,000 worth of land THERE. (In Mississippi I had just bought 4 acres for that price).
I also gained about 6 inches on the other side
Good fences make good neighbors, but it takes good surveys to tell where the fence should be.