Not quite sure what you are getting at. A DP can serve a fair number of premises, each house does not have its own exclusive DP.
The CBT serving my place is a 4-port unit, but I'm aware that CBT's range in size from 4 ports up to 12 ports.
To the best of my knowledge on Openreach CBT's at least, there is no optical splitting inside the CBT, the ports within the CBT have individual fibres spliced back to a DP which I believe does have a 1:n optical splitter in the trays.
Can any Openreach folk provide any more detail?