Ring Alarm Motion Detector placement

Hi all, I have a 1st generation motion detector that I'm trying to figure out where to place it. I did read this: https://support.ring.com/hc/en-us/articles/360039498552-Ring-Alarm-Motion-Detector-Setup-and-Use However, I still have some confusion about how to best place them and the purpose of the motion detector. 1) The motion detector is to detect movement in case if someone breaks into my home, correct? If so, should the motion detector be placed in a spot where it will be able to sense someone coming in through the front door or windows in an attempted break in? I'm just trying to understand the exact purpose of Ring's motion detector. 2) I have a split level home. When you first walk into my home, you have the living room in front of you, 5 steps that lead up to a hallway landing that's open space. Should I put the motion detector in the opposite vantage point of this room from the entrance way? Where the wall meets the ceiling in the opposite corner is 12 feet high. Is that too high even for a 2nd generation sensor? I could put the sensor into another corner...from where you enter, if you look to the right, there's another corner that's 92" (about 7.5 feet). Height wise, that's where Ring recommends the motion detector. But, if I were to put the motion detector at 12 feet high, is that too high for the motion detector to sense movement coming from the front door? If so, I should put it in the corner that's 7.5 feet high? I appreciate any help clarification you guys can provide. If you need me to post pictures to help visualize it, I can do that.