Lifetime of FreeBSD branches

[Francisco Reyes]

On Tue, 24 May 2005, Scott Long wrote:

> Again, please don't take the abrupt switch to 6.0 to mean that 5.x is
> flawed or that 6.x will also have a short lifespan.  The real purpose
> of the switch is nothing but positive; it'll keep us focused and prevent
> us from overreaching and overextending ourselves.  It's a very good
> and very postive strategy.

So why have a 6.X naming convention to begin with?
Why not just stay in 5.X name wise?

Is there a thread that sheds some light on that topic?
Is the goal to have a new major branch every 2 years?