Multiple pieces or single...Pt2

I asked this question about hard surface models once and Sanctary was very helpful, now I was wondering about organic for animations. Can I model say a robot in different pieces, arms and legs for instance not connected to body, and not run into issues when rigging.I am starting to learn the rigging process and appreciate any help with it. Do arms of a humaoid or creature HAVE to be attached to the body? Purely animating in mind here, for games.

For robot parts you can have different object for it. Just parent those objects to appropriate bone.