Well not to argue with the masters but you guys obviously haven't put together AM armor in a while. Trying to assemble overlap armor, butt and strip style is a nightmare. Using inner cover strips simplifies the process significantly. So in some instances inner cover strips are beneficial in the assembly process.
For the record this is NOT AM style armor (that we're aware of), Mathias & Dday are correct however, the only reason I use them beside reasons already mentioned is to give the interior seems a cleaner look, but that's just me so no browbeating me about it please.
Cheers