I am not one of the most experienced members but in general you mount a ptz there where you have visibility of every spot you want to see with it.
Low install is in general better for identification, and high install better for overview.
Personally i have experince with a ptz at like 8 meter high, but i need to look over a 3 meter high garden wall which is 9 meters away from camera to see my car installed on public parking space. (That is like 20 meter away from camera)
Image is great, but the car burgulars tend to have hats on and look downward a bit. So identification is not optimal. Also i look at straight line to car, the traffic movement is at 90 degrees, so you see side of people heads, cars from the side etc.
If i move house i will install all cameras lower than i have now for better identification..
Ptz will be at 260cm high. We are only allowed to film own property in basis, and the garden walls can only be 2 meter heigh legally. (The current 3 meter high wall is 5 meter from the property border and belongs to the concept of the block of houses)
So I will be able to see people climb over the fence basically and see in straight line what is behind that (trees or street) but no walking people on public road.
So general advise from me:
- get your requirements clear: what do you want to view
- a ptz can only look at one thing unless you programm a tour, or have external trigger that moves it to a preset.
- do not think your ptz will cover it all, even with tour or triggered presets, you will need overview cameras for that function.