Every post gets two bags of post-crete, well above the recommended amount, because a fence is only as good as what's holding the posts in the ground.
A typical fence job starts with removing the old fence carefully, especially where a post is fixed to something else, like a deck frame, which then gets made good so it stays solid once the old post is gone.
Holes are dug to a minimum of 60cm deep. The first two posts go in along with a gravel board, and from there the gravel boards and panels are used for sizing as the fence line goes along, making sure every post holds the panels tightly rather than leaving gaps. Every post is set with two bags of post-crete, well above what's usually recommended, because it's the difference between a fence that stays solid for years and one that starts leaning after a couple of winters.
Materials, panels, posts, post-crete, gravel boards, are priced separately from labour and charged at trade cost. Material prices are taken from supplier websites and can fluctuate slightly, though trade discount usually brings them in a little cheaper than the figure first quoted.