I should also note, I am usually on the high end when it comes to cedar siding. But I have seen some real junk installed due to rushing the job.
We use combination corner posts, most guys double up 5/4x4. Our method take a bit more time but looks stunning. We caulk the butt joints to delay water penetration. I recently saw a job where not a drop of caulk was used anywhere. Sad really.
Good luck!