When do you move and sew?

YellowYeti

So this might be a bit of a dumb question, but just asking so i fully understand it, when you unwraps UVs in maya when is the proper time to move and sew objects together than just leave them be? It seems like you would move and sew and try to make them all together if it's a plain hard surface that will get about 1 generic texture, but i've seen things where for an axe they kind of seperated everything out a lot ie the axe head instead of leaving it together. I can kind of imagine why an organic model you would want to keep everything as connected as you can. Thanks!

CharacterCarl

It is in the nature of textures that their UV maps need to have seams and multiple islands (unless you're talking about a single, non-overlapping surface), because you're mapping two dimensional image files onto 3-dimensional geometry. Even for organic/connected models, you will have to make do with seams, as leaving everything as one island would result in overlapping UVs.
As for organic models, it is common practice to use them in places which are easy to hide (below characters chin, underside of their arms, back of head if it is covered by hair, etc.). As for your axe example: Apart from having multiple sides, for props you will most likely have parts which are more important and more often seen by the player. By separating the islands and giving these areas more room in the UV layout, the artist can allocate more resolution where needed. 
There is a special meaning of uv islands when it comes to baking and hard edges, but you'll learn more if you check out some of the sticky threads or the wiki:
http://wiki.polycount.com/wiki/Texture_Coordinates
http://wiki.polycount.com/wiki/Normal_map