Yes, I agree with your time frame analysis on the French Revolution. The same is equally true of the American Revolution. The actual period of the Revolutionary war was preceded by an extended period of extensive social change that laid the foundations for much of the cultural change that followed the Revolution. I think cultural change is a constant process, at times glacial, at other times quite rapid and occasionally explosive and quite destructive. I think cultural change becomes destructive when impediments are place in the way of the natural progression of social change as it seeks to aligns itself with natural processes.