I have a scenario where occupancy control is desired in a home office setting. This will be mainly for desk activities, so sensitivity would have to be high. However, there's an adjacent entry hallway where line-of-sight from the ceiling would be problematic. As in, it'd pick up motion out in the hall that would not be desirable to determine occupancy in the office.
I employed a ceiling unit in an L-shaped master closet in the residence and found it necessary to use a bit of white tape to block the sensor's coverage out a nearby door. There wasn't anywhere in the room that would have been effective for wall or corner sensors. That's worked, with the small requirement that the unit be put back into the ceiling mount in the same orientation every time. A mark and label in the the mount indicates this for when the battery needs replacing years from now.
A corner unit might work, but I don't know if it'd be sensitive enough to provide enough sensitivity for seated positions. Is there a spec sheet that shows the vertical spread of the sensor? The ceiling one does, but the wall one does not.
It's sometimes a challenge finding the sweet spot for detecting motion in ways the occupants "think it should".
What, if any, issues are there if there's more than one sensor covering the space?