Re: How many times?
"In most areas it is is far more economic to have infrastructure provided by a single organisation. AND THAT CANNOT BE BT or OPENREACH"
It can be Openreach - look to New Zealand and the TelecomNZ -> Spark/Chorus split and demerger.(*)
This was specifically done after TNZ proposed the BT/Openreach model - the competition authorities there studied how it was working here, noted the ongoing market abuse by BT and said "No. Full split. If you want any more broadband money, you'll do it without arguing"
The last part is what convinced TNZ not to argue. Losing a few billion income and having lots of stuff they didn't want disclosed dragged out in courtrooms was the key - it would have exposed them to extra litigation with court evidence in one case being used to prove liabilities in dozens of others.
Once freed of the tyrannical hand of head office, the newly freed up "Chorus" rapidly started hunting down new customers and providing good service to all comers. Former "competitors" were now potential clients and the equivalents of Virgin are able to lease dark fibre or run their own cables in Chorus ducts.
The result is that Chorus is robustly healthy(**), even with regulated copper/fibre prices (which are going down on copper pairs, despite Chorus' objections - the idea is to force the country across to fibre by making it more profitable than copper) that started off at about half the previous monopoly incumbent pricing and are now significantly lower than that.
The ironic part is that the former incumbent is now rather sick and struggling to get financing, even crying poor and that the newly regulated lines pricing was far too high(***) - demanding a special discount (which it didn't get). Everyone else was happy with rates that had been halved and not having to use telco-supplied NTUs on tail circuits, etc(****)
(*) Share split, issued to existing shareholders. Complete split of offices, directors and CEO. Telco kept its exchanges and distribution plant. Lines side company got everything from the MDF outwards and all supporting outdoor plant. Lineside copper rates regulated. Dialtone supply not mandatory for *DSL, rules put in place limiting maximum shareholding by any one entity, to prevent takeovers and any shareholders over that limit at divestment given a hard deadline to sell their holndings down
(**) Despite dire predictions of not being able to get finance (proven wrong), pensions liabilities (proven wrong) and inability to get business (proven extremely wrong). It's taking on more staff to keep up with demand and quite profitable despite regulated line rates that everyone's(+) happy with.
(***) Line charges were set by the ministry of commerce after consultation and using figures supplied by Telecom New Zealand. 12 months on, the screaming from Spark(formerly TNZ) made it clear how much of a cash cow that the lines business had been. The myth of the "sick lines company" had already been pretty much exploded by then, but the fact that the former incumbent dialtone provider was whining that lineside charges were too high to make a profit underscored how much they'd been ripping everyone else off and hiding the real situation by creative accounting. They were fundamentally dishonest with the figures they supplied the regulators and thought they'd get away with demanding special deals later on. It didn't go down well.
(****) This is a backdoor way of holding your competitors to ransom. Putting NTUs on means you can charge far higher leased circuit rates instead of dry pair rates. Telecom NZ withdrew all dry pairs in the 1990s when they realised people were buying and installing their own NTUs (and managed to cancel the type-approval for all non-TNZ-owned NTUs). As with BT, what that means when you buy a leased circuit from a competitor is that unless the competitor has physical connectivity to your premises the "last mile" is across a subleased BT circuit, meaning that there are actually 3 sets of NTUs in place (BT-BT--XYZ-XYZ--BT-BT) resulting in the cost for such a circuit often being higher than buying directly from the incumbent AND the BT/XYZ interconnect causing major issues(++)
(+) well, almost everyone. The former incumbent is still getting used to the idea of not being able to hold the country to ransom.
(++) Our painful experience with this was that whilst faults on our 1GB/s line were invariably BT equipment, Virgin wouldn't call them until they'd had a tech onsite to verify the problem and then we had to wait for the BT tech to show up and fix things. This added 18-24 hours to circuit restoration times. Unsurprisingly we've gone back to BT but only because they're no viable alternative (Because we went to Virgin, BT immediately dropped the price they quoted by 55% - and THAT is how a rapacious telco can hold everyone to ransom. I'm quite sure that come contract renewal the prices will bounce up again, now they have us back in their sweaty paws.)