He's just have a different, non-human limit to his chakra.
We have seen people have to cancel jutsu because they can't sustain it any more even when their chakra supply isn't out. Shikamaru's jutsu comes to mind.
I've seen Shikamaru cancel his jutsu because he knew he wouldn't be able to sustain it and wanted to leave chakra for later. I've never seen him WANT to continue using it and running out, even though he still has chakra left. I've never seen anyone run out of the ability to use a jutsu and still having had the chakra left to perform it.
He did during the Hidan fight. Hidan noted there was a time limit to it, and that he had to release and re-establish it occasionally, and each time the time he could hold it got less.
OK, but when Danzo did Izanagi, he canceled it just because he needed to conserve chakra, not because it was too hard on his body (though it also extinguished his eyes for a secondary time limit). Rikudou doesn't have either problem so I don't see why he couldn't keep it up.
omg, im so sick of this argument. dodging someone shooting a beam of light at you does not make you faster than light. If you waited till the beam was shot and then moved, that would make you that fast.
What luffy did was move faster than the pacifista, not the light it shot at him. Also, I don't think they ever said that those are "lasers" he said beams, but a beam does not mean it is light, though I think it is a laser, just saying, we don't know
oh yeah, i agree its crazy awesome, I mean as a team the strawhats BARELY took one of those down, and he took it out in one punch, after dodging an attack with ease that he was scrambling to dodge before, yeah its amazing . and I would LOVE to see luffy in the naruto verse, obviously tehre would be some conflicts, which ther always is with mixing verses, but i think he would doinate pretty much everyone
PERHAPS HE WOULD DO WHAT NAGATO TRIED TO DO TO NARUTO. AND THAT IS JUST TO DISPLAY THE AMOUNT OF CHAKRA AND CONTROL HE HAS. COMBINED WITH THE ILLUSIONS HE MOST LIKELY CAN DO, AND SEE THROUGH HIS MOVES, AND WELL....ANY JUTSU EVER.