I've been looking that the numbers for offense troops and defense troops. It seems that it is much easier and more cost effective to focus on building offensive troops, and only keep enough defense troops to do the battle grounds. Especially for low to mid level players, defense troops in a hamlet or settlement are basically a neat way to blow resources and give someone else pvp points. 

Is this accurate? It seems like you can hide resources or use them up quickly if there is a raid incoming, and if you ever were sieged, it would be your offense units used to liberate anyhow. What is the point of defensive units other than completing battle grounds?