In centralized version control, is it always good to update often?

Assuming that:

Is a “model” branch a common practice?

I just thought it could be a good thing to have a dedicated version control branch for all database schema changes and I wanted to know if anyone else is doing the same and what have the results been.

Shorter release cycle with DVCS

Does the choice of using a DVCS over a CVCS actually make for shorter release cycles? If so, what makes software release cycles shorter and what are the arguments for this?