It's technically better to "center post" your coils since there's more room behind it for vapor to mix with air, and also the airflow doesn't hit it at an angle, it's directly in front of it. However some think it doesn't matter (it doesn't make a huge difference, but I like to when I can), it does add a little more wire to your build though, so keep that in mind, to maybe subtract a wrap so the ohms don't go higher than you want. I personally wish there was a 4 post atty where the posts are ready to be build in the center of the outer wall, so that you don't have to stretch it over like these:
Trick as hell, but so satisfying once you got it in place.
The airflow doesn't hit at an angle with a non centerpost build if you position the coils properly.