It definitely depends on the invention in question. Consider the case of nuclear weapons. The first big leap is that the energy of fission can be made to be e

It definitely depends on the invention in question. Consider the case of nuclear weapons. The first big leap is that the energy of fission can be made to be explosively released. Once you know that this is the case, most people in the field might be able to come up with something along the lines of a gun-type warhead. On the other hand, implosion devices, even if you know they are possible, still require a huge amount of work and design studies to make work reliably. Knowing that they are possible isn't the hard part--making it work is.