Depends - on weekends it's always yes due to the 50% off on tower of dragons stam cost. On normal days yes and no - the xp of a full bar doesn't cover levelling, but you also need to consider the amount of time spent actually running the dungeons - depending how quick your team is you have a good chance of regenning enough stam while you are running them.Is it even possible, after a certain point, to get a rank up out of your stamina bar? Some of the dungeons are just horribly inefficient, but even the ones that are "good exp" don't seem to move it enough. Speaking of inefficient, Thursday Dungeon is around 33 exp per stam!
There's not really a lot of point in powerlevelling though, unless you have good stuff you can't use due to team cost.