Depending on the dodginess of the fence contractor, the posts are often short and the concrete job sucks. On a typical fence with ~6' high panels, the posts often extend above the panels. That leaves 10' posts less than 48" down or 8' posts hanging on by magic. The bigger and deeper the footing, the more you need to dig and the more concrete is required to fill your hole. I've seen some with the wood going down a ways but the concrete as a collar in the top 18" so it looks like it was done well but it is guaranteed to frost jack. They often also mix the concrete like soup as water is cheap and it is faster and easier that way even if it is crap strength, etc, etc. You can't even get them to show up to give you a price, do you think you can get them to come back and fix a substandard job?I'm no expert but to me that looks like a very temporary fix if you just drove the spikes into the ground with no concrete. But at least it was cheap. I guess it also depends on how much wind the fence receives, eg if it's right next to the house and the house blocks most of the wind, vs my fence where the fence receives the full force of the wind. I guess the guy who built my fence didn't do the posts/concrete properly if the concrete is rising out of the ground. I have another fence on the other side of my yard and that fence is still perfect, so the guy that built that part must have been more experienced. I think it's more complex than simply digging a hole and putting a 4x4 in it and putting concrete around it, there is a technique to doing the concrete if you expect it to last. I read you are supposed to make the concrete in a pyramid shape which prevents it from rising out of the ground.