I agree. Searches by individuals will vary because of differing abilities and approaches. Familiarity is also a factor. When searching someplace so familiar as their own home or yard, a person may gloss over potential hiding spaces or dangers that might stand out to fresh eyes.
Residents have been very cooperative, according to the police. I'm certain the neighbors who searched their homes and property intended to do a thorough job. Some of us are good are finding misplaced items, however, and some of us are not. Abilities vary. Thoroughness and intensity vary. What seems like a thorough search to one person may seem cursory to another. A possibility one person thinks is worth checking out might seem too improbable to another.
I think there is still a strong likelihood Michael is in the immediate area that was searched and either he came onto the property after the search or was missed in the initial search. I hope yesterday's appeal for people to search their properties again leads to clues or a resolution.