I know using multiple Canvases is supported in Unity, but is there any good reason to do this? From my understanding, adding extra Canvases will just increase draw calls when you could just as easily handle management of UI elements via the children of a single Canvas. Originally, I thought I needed two Canvases if my UI was partially 2D (Overlay) and partially 3D w/ perspective distortion (Camera), but now I'm not even sure of that. I reworked my UI to use a single Screen Space - Camera Canvas and I just leave all my 2D elements at the specified camera plane. Seems to work like a charm and I don't have to worry about managing draw order or raycast blocking across multiple Canvases. Now I'm guessing that at most a single Screen Space and single World Space Canvas would be all that's really necessary for any UI. Thoughts? Counter-examples?