The engineering teams just dont work on one exchange area at a time, they are sent to where their needed by Openreach, it all comes down to the project managers and how they manage the resources they have to move the rollout forwards.
That is a better explanation than the "blocked ducts" thing. I appreciate the teams work multiple exchange areas as I've seen them working Stechford, Acocks Green and Hall Green Exchanges.
As some people see, they seem to have a flurry of activity on a certain number of cabinets and then spend forever sorting out the fibre on the rest as they focus on other Exchanges. Which is incredibly frustrating. I look at the next cabinet geographically and think - "that's 100 yards over the road, why do we need to wait another 3 months for the fibre".
It's completely mind blowing when I've seen them do the work one day and the cabinet is active the next. If there is planning, it's just bizarre! Just incredibly frustrating having Cabinets bypassed, or cabinets installed but missed out for fibre during the initial roll out/.