I think I still hold the record number of 11 times, for hitting the same phone cable, within the span of 3 power poles, approx. 600', in our county.
Phone company was called to mark, and did. At the end of that span were two junction boxes for house drops. Locator guy dug down to verify the cable was buried at 36" per their specs. He assured me it was that deep clear through. I told him it had better be.
Sloping a bank with a Huber F-1000 grader, I started cutting the slope. At the top of the slope was a plowed field, and the last furrow, approx. 7' - 8" deep, was plowed inward towards the field. A good gauge to use to start the cut.
At that depth, I cut the line 11 times. The same guy came out to repair it 11 times. On about the 8th one, he asked me, "Do you realize what these splice kits cost apiece"..?? I told him I did not care, he assured me that line was down 36". And that's not even close to 36".
He told me the cable was installed by contractors, and they get paid by the foot. More than likely, it was put in in the summer when the ground was dry and hard. A lot of them back then used those little Davis 4-wd trenchers, with the vibra-shank plow. When 6 to 8 feet from the junction box, they would pull the plow up, so as to pull easier, making time, and profit. Besides, who will ever know..??
The phone company agreed to install a new line, once we were done, to the proper depth, at no charge to us...