Very clever! With motion sensors, placement can be essential to accurate alerts.
BTW, Different motion sensors have different viewing fields, so it depends in part on which sensor you select.
With almost all PIR sensors the field expands as you get farther away. So sometimes it’s just a matter of where you’ve placed it. Farther away sometimes works better than close up.
Also note that the sensor is catching tiny changes in temperature as they move across the sensor. So these all work better when you position them so that you are walking across the sensor field rather than straight on towards it.
Enerwave makes a Z wave sensor which is specifically designed for ceiling mounting and is worth considering:
Mike Maxwell also has an excellent smartapp which can combine multiple motion sensors into one zone and react whenever any of them are triggered. This can be useful in very large rooms or rooms with nooks or an L shape.