As I price an expansion of my fenced in area I have a little more information to work from. Poultry netting holds up pretty good through four years. Black plastic insulator materials is very much failing by 6 years. Over last couple months I have had a lot of fencing issues where the black plastic is becoming so brittle as to fail making for a short. The yellow insulators have yet to fail. Neither does will when too close to prescribed burn. Metal T-post and fiberglass post rods look like they can go another 20 years at least.