I've done that. Walk around banging on s*** to wake up the zombies. I'm not quite as thorough as you are though. That takes some patienceWalk through the POI from start to end, and smack a metal object in every room, or open and close every door twice, usually helps me, but I'm the kinda player who starts on the morning of a day, and doesn't finish until the next morning (I harvest everything, dig every bag of cobble/cement, check every nook an cranny for a possible weapons bag or ammo pile)
Thats the one I see/hear people miss the most, as there isn't much loot in that area (like 3-4 trash piles, 2 bookcases that usually are empty, and 1 duffle bag in the cistern"One place in the water works that's easily overlooked is the small room off to the side that is protected by a dog. There is one sleeper inside.