To expand on what Osmium said, a "golden age" is more like a "goldrush age": A big breakthrough opens up a new conceptual frontier, and the golden age is scientists rushing in to homestead and start mining the new landscape.
This isn't to say that all progress is done in goldrushes, but the most basic and, therefore, best-known work of a given field will be done in that period.
There's no continuum because some things are harder, others are easy.
Computers have evolved pretty much "continually" since the personal computer era, but they took some time to be invented.
Quantum mechanics evolved "quickly" once we found out there was such a thing as quantum mechanics, up until them it was a lot of "banging heads" and freewheeling.
Not to mention delays because of other constraints: wars, political instabilities, etc
This isn't to say that all progress is done in goldrushes, but the most basic and, therefore, best-known work of a given field will be done in that period.