A mode is nothing more then starting and stopping a parent scale (major/Ionian, Melodic Minor, Penta, Etc..)on a note other then its' root.

Understanding how to utulize this concept to it's maxium ability when creating music is a bit more in depth.

So to answer your question: yes, all modes can be played in 1 pos., but you would definitely be limiting yourself by not learning them in every posiyion possible on the fretboard.