Board Thread:Episode Discussions/@comment-1512913-20180906224733/@comment-31099706-20180911115858

Elveonora wrote: Still doesn't answer my question, how come during the Pain arc. they had sensing barrier, but other plot events ignore such a thing :P Well, I think it costs alot of chakra and needs to be mantained by other shinobi. In the Pain Arc, everyone knew Pain was coming, so it's obvious that they would keep their security to the highest possible. There are probably people checking on the barrier, and it may not be that easy to do it.

During this period/episode, everyone was called for a meeting, possibly even the Jonins that held the barrier, or the barrier was only used as a measure to protect against Pain. It probably does cost alot of chakra and focus, that not everyone can do it on a daily basis, without any threat during that time. Remember, Shikamaru also mentioned that they have friendly relationship with all the villages, showing that they literally have no reason to go over the pain of using all their resources for a barrier, when everyone seems at peace.