ECI is a complete failure for Openreach it seems.
It is certainly a complete breakdown of trust. BT simply don't trust ECI's quality control processes - that what they say they've fixed is actually fixed and tested. *And* that they haven't broken something else.
The current test cycle (s l oooooo w) is a consequence.
What I don't understand is why they need several months to assess it, surely 3 months of data is adequate?
I believe that BT employ a network freeze for Christmas - quite possibly for the entirety of December.
In a test like this, then, they need to be able to roll out the change, and be happy it finished successfully, while still allowing enough time to undo the rollout completely before the freeze starts.
From the most recent report, I suspect that BT have decided they're happy to leave "a few" running over winter, and will aim to rollout properly next year. In the meantime, ECI probably get to do a fair statistical analysis on the outcome.
Aside: (The reports on progress earlier this autumn actually made me doubt "the freeze", as it looked certain that BT would have to run into this period. I'm "relieved" to hear the current status, at least as far as my understanding of BT's behaviour goes).