Today, the many spinoffs of physics in general can lend support to branches that haven't produced spinoffs yet. But what about the first developments in physics? How soon after Newton's laws were published did anyone use them for anything practical? Or how long did it take for early results in electromagnetics (say, the Coulomb attraction law) to produce anything beyond parlor tricks? I don't know the answers here, and if there were highly successful mathematical engineers right on Newton's heels, I'd be fascinated to hear about it, but there very well may not have been.

Of course, theory always has to precede spinoffs; it would make no sense to reject a paper from a journal due to lack of spinoffs. To use the heuristic, we need some idea of how long is a reasonable time to produce spinoffs. If there is such a "spinoff time," it probably varies with era, so fifty years might have been a reasonable delay between theory and spinoff in the seventeenth century but not in the twenty-first.