Well your exchange has around 112 cabinets serving ~28.5K lines, most of which are already live, I can even see a cabinet supplying around 9 lines, how that got BDUK funding I don't know.
I can also see that your cabinet (i.e. 27) has passed 480 odd properties which is located
here, but by the looks of it, it looks like it has a small fibre cabinet which is why there is a waiting list atm.
I worked it out as 1km give or take a metre or two, from that postcode and the cabinets, that's if I picked the route they placed the cables.
So on average that's 255 lines per cabinet, that's not too bad.
As for closer cabinets, well that distance is fine for phone lines which is what they was originally designed for.
Also new house builds get built, its normally the developer that is responsible for this and going by the type of PCP Cabinet its been there for many years now due to it being made of cast iron.
I would wait for G.FAST to be rolled out, that should increase your speeds a fair amount.
No point giving you any email addresses at BT / Openreach due to none of them will probably answer that question.
But looking at the map they seem spread out ok to me.
Paul
BTBroadband - Infinity 4 - 310Mbps (down), 31Mbps (up)
TBB Speedtest