We hunt cow carcasses that the ranch dumps. Takes about 3-4 days for the coyotes to come around. Once they're on it it lasts about 5-6 days. Usually set up about 200yds from and they still bust us from time to time.
Bad thing about baiting with small items like guts and pelts is that the coyote won't stick around to eat it, he'll get it to go. I dropped my deer remains in one spot, came back the next day 10 mins before sunrise and almost everything was gone.