Trying to classify generations like this is dumb. I mean, depending on what cutoffs you use, I am apparently supposed to identify more with people 10 years older than me than people a few years younger than me.
Part of the problem here is that societal attitudes evolve at a much faster rate these days, such that 20-year generations are not really a useful sociological concept. I already see a pretty significant difference in attitudes and outlook between my peers and people just five years younger than me.
Part of it, sure. But you still have the issue about people born near the cutoff dates, regardless of where you actually put those dates, even in older generations.