I noticed that in a lot of videos people will make objects that have two or more overlapped meshes, such as a gun made of a barrel, magazine, etc. and they look fine, but I would assume this would cause issues for rigging, animating, and even reduce performance in a game engine due to the internal geometry and separate objects, wouldn't it? (not talking about z-fighting)
Is there any problem with making an object by just overlapping two different ones, with no geometry connections?
For example, if I was to create a windmill that I wanted to easily rig and animate and export to a game engine, should I create the windmill's sails from the geometry of the windmill and keep it as a single object, or should I create a new object and make the sail then Boolean it so it's 1 object, or instead just leave them overlapping?