When we at Infinity Fence dress our fencing we do so by using 2 x 4 brackets, which we attach to the sides of the posts, thus giving us a nice clean look and allowing the pickets to run the center line of the post. This also gives us a nice proportioned look to the front and rear dimensions of the fence construction. (See Infinity Fence Typical Bracket Install in this album.)
Here, our competitor chose an installation that is quicker, easier and less expensive than using brackets. While this is not an incorrect installation, you see how attaching the 2 x 4 backrails to the inside face of the posts leaves you with an added inward dimension. It also leaves you viewing the seams where the2 x 4 backrails meet on the post. The pickets also no longer run the center line of the posts (this can be seen on the picture further on in this album titled Picket Lines) and leaves an excessive amount of post sticking forward of the section (not pictured here).
Again, while this is not an incorrect installation from a structural standpoint, aesthetically, it is not one we recommend.