When I think about branding a generation, which is always done by a member of a previous generation and with not a little whiff of "kids these days' syndrome, it occurs to me that there might be a feedback loop involved.
If you're firmly part of Generation G (for Generic, a theoretical generation) which has qualities X, Y, and Z but born in the mid-to-late period of said generation, you're told from the moment you're born that you're part of a group that is X, Y, and Z.
I don't have an answer, but I suspect that the problem with 20-30 year-spanning "generations" which are defined and classified by older folks is that, over time, they take on the qualities imbued by an outside observer.
If you're firmly part of Generation G (for Generic, a theoretical generation) which has qualities X, Y, and Z but born in the mid-to-late period of said generation, you're told from the moment you're born that you're part of a group that is X, Y, and Z.
I don't have an answer, but I suspect that the problem with 20-30 year-spanning "generations" which are defined and classified by older folks is that, over time, they take on the qualities imbued by an outside observer.