big part of why a ton of people theorize hes lieing about being madara is about him never having a non-3tomoe eye, either off totally or EMS, as far as never turning it off his chakra was supposedly why hes stayed alive so long and hes an uchiha so they take almost no chakra to keep their sharingan active unlike kakashi.
we don't see his eye when hes using his space/time powers so its possible he only changes his eye into EMS during those few seconds but so far we've never seen "Tobi" with his sharingan changed.