Regarding whether a second or so is enough following engine failure, I was at a CAA safety evening last night where they touched on helicopter fatal accidents in the UK over the last eight years.
There were about 20, only one of which involved engine failure, and that resulted from neglect of carb heat.
Most of the remainder were bad attitude/poor decision-making. Loss of control in IMC. "Ran into high ground in IMC at night." In an R22, yet.
A second may or may not be enough in case of engine failure, but we can make decisions on whether or not to fly at our leisure.