Thanks that's interesting. They are supposed to be 25 year posts. CCA lodgepole pine, ACQ Doug fir, and Penta Doug Fir are the only posts readily available here. All 3 that are sold locally here in our experience are poorly treated. Virtually zero penetration of the treat! The pines would last 5 years give or take a few. Not good for business to say the least.
We import these from Canada, they are not AWPA certified, but do meet Canadian ministry of agriculture and BC highway construction standards. There are several that were installed around here in the mid to late 90s as part of VSP trellis systems, still standing strong. In recent years trellis installation has gravitated towards all steel.
We've experimented a lot with posts. We had one customer specifically request ACQ Doug Fir, within two years the fence had experienced approximately 50% post failure.
And of course all our steel posts are still standing.