I think in terms of paradigm shifts they do happen within a few decades. Progress isn't a straight line (evolution isn't either), there's a long time where nothing happens and then a sudden rapid seismic shift and then a new plateau. Evolution worke the same way but to get evolution to work rapidly, you historically first need a mass extinction event and then nature rapidly fills those specialized environments with new species that can survive under new conditions (on evolutionary timescales, 100,000 years is considered "rapid.")