I just redid my kennel lot, removing 4"x4" PT posts planted in the early 90's. Used Quickqrte on most of the posts.

These were 8' posts set 2' in ground, none were rotted below ground that were set in concrete, a far more serious problem is termites, than time decay.

I went with 3"-4" & 4"-5" round PT 7'& 8' pists on the new fence, also placed with concrete, or either Crush Run Aggregate #26.

But I built a dog lot, you are building a nice residential fence, use the best posts you can afford.

Growing up, we had a two sided fence similar to this but narrower gaps:


Nice privacy, let more wind pass through, and looked nice on both sides.

When I lived in Alaska, I had the galvanized metal posts with my wood fence. Few places in the world will have more frost heave than Alaska, and I left the brackets loose and let the fence "float" on the posts as they moved up and down. My gate post was a 4x4 set in concret and it snapped off in a Chinook (12+ hour windstorm. Wind speeds like a hurricane but straight line winds). I couldn't get my jacks to lift the concrete out of the hole and had to get a contractor to get it out.

Someday, I'll get to build a house and combine the double sided fence from my childhood with the galvanized metal pole like Alaska.

The fence was already built when I bought my current house. It's a shared fence, and the builder alternated every other panel on who had the nice looking side. It's a pretty good option for a shared fence. Here is an example pic: