Sanctuary Hills is the worst for the AI.
After given jobs to settlers and playing the game for 8-10 hours the AI stops working for most of the settlers and there jobs and they just stand in the way of doors and other places.
It can take over 10 min of game play in Sanctuary Hills before some of the settlers will move and go do there jobs but only for the ones who takes care of the garden, all others will still stand around and not do anything at all.
I wanted to use Sanctuary Hills as my main base but after 10 hours of play it breaks the AI and nothing I do seems to fix it.
Before you ask, no I do not have any mods and it got worst since the last patch through steam.
It is also happening in other settlements to not just Sanctuary Hills.
GeForce 660 Ti, quad core 3Ghz, 16 Gb Ram.