I always have 4 cameras MAX,, per supply but I guess it depends on location and distance and current draw of cameras, some high power bullets can draw an amp.
On a typical Residential property I home run all the power but on larger Commercial and cetainly when installing PTZ's or SpeedDomes I like to install the PSU local the camera !
If the budget and space allows 1 camera = 1 PSU if the power supply fails it doesn't knock out the other cameras
Hope this helps
AL