Hey,
With a Weissbier I would alway pour the bottle until there is about 1-2cm of liquid still in the bottom and then give it a good swirl and pour into the glass. I much prefer the flavour it gives to the beer. I'm not sure with other beers if, by swirling, it enhances the flavour. But I don't think it can do any harm.
Ultimately I think it comes down to personal preference.