Fascinating technical subject this, and I am not too well versed in the details, but I believe that beyond a certain point, counterflooding is catastrophic. As the ship gets lower in the water, the metacentric height gets lower and eventually the ship will roll over, with little warning. I have no idea at what point that might have occurred with Titanic, but I suspect that it would be sooner than two hours, given the amount of counterflooding necessary to counter the weight of the five flooded forward compartments.

In any case, such counterflooding could well have "hogged" the ship; with the ends flooded and the midships section buoyant, the bow and stern could have started to break off.

As regards "Ark Royal" etc. RN damage control in World War II was patchy. Most losses were due to failure of electrical power, preventing pumping, firefighting etc. "Ark Royal" lost power, so did "Prince of Wales" (where an engine room flooded because of a hit on the 'A' frame supporting a propellor shaft).

Several ships which should have been goners made it home, some of them still fighting, if the electric systems still worked.