It was pretty ineffective.
The system seems to be encroach, and then demand the airport close/change.
We think about the terrain, but not so much what's built on it. Light aircraft people might keep roads or cleared areas in mind, but not much use or interest for the bigger aircraft. I guess Sully's use of the Hudson might count, but I dare say that he'd never have previously considered ditching there.
There is no V1, when no options exist. Some aircaft would be able to fly away with the loss of an engine during the cat shot, and their pilots would be primed to jettison any stores, but it would very quickly be followed by ejection. Once that catapult fires, you're going.
V1 isn't the last speed at which you can abort after an engine failure, but it's actually the first speed from which you can continue the take off. In some cases of extremely long runways, it might be possible to abort from a higher speed, but we need that decision to be black and white, so any grey areas are ignored.
There can be a nominated rejection speed. For instance, I once flew on a KC135, way back before they were given modern engines. The aircraft was extremely heavy, and it was very hot. They had no V1 as we know it from airline ops. There was a refusal speed. The first speed at which they'd be able to fly away on 3 engines, was quite a bit faster than the refusal, leaving them with a gap when you'd be too fast to stop, but too slow to be able to accelerate and then fly away on 3.
