I see it as a 'supply and demand' costing exercise. No business is going to over-estimate the take-up of a product, that would be financial suicide.
Walter, you state it's "obvious" the full capacity will be required at two particular Cabinets in your area. Try approaching your bank manager and ask for a loan to provide FTTH for the whole of Surrey, based upon the fact it's obvious everyone will purchase it. Poor anomaly ?? Possibly ? ............... but the issue is no business is going to work on 'If's, but's and maybe's'.
Additional 'civils', should expansion work be required, are not this problematic animal that is being alluded to. A bog-standard FTTC set-up, could see the 'Dig' work done, additional duct laid, surface reinstatement and cables pulled in, within a day. The extra 'civils' may not be required on a high-percentage of expansion tasks, as the in-situ ducts may have the capacity for the extra cables needed ?? The planning department have access to the 'Prints' that show all duct capacities.
I promise you guys, BT know what they're doing. They've been doing it for a lot of years, are a global leader in Telecoms, a blue-chip company who are showing healthy profits even through the triple-dip recession. If you haven't already got shares in BT, get them now by way of a mid to long-term investment, as they will grow as our hold on streaming TV grows.
Yes, they make mistakes, I see them daily at a lower level, but regarding this particular debate on this thread what you guys see as you walk past an excavation, or gain from chatting to a low-level engineer, doesn't mean that that is necessarily the whole picture. Plus, there are always going to be anomalies, but percentage wise across the many thousands of Cabinets supplied with FTTC, these will be miniscule to the nth degree.
I reiterate, they know what they are doing ................ that's why they are a massively successful business.