He couldn't just enter one world to learn Spiritual Power, unlock a Soul Ring in the next, and then cultivate battle energy in the one after that, right?
That would be a chaotic mess.
Setting aside whether he even had the ability to learn all these Extraordinary Powers, even if he did, would he have enough time and energy? Could his body even contain so many different types of power?
If he learned a jumble of them, wouldn't he risk going insane, or having them conflict with each other and burn him out from the inside?
And yet, the future instances he might enter were bound to have special abilities driven by unique Extraordinary Powers that would be either very practical or incredibly tempting.
What if a power allowed him to reshape Heaven and Earth? Should he learn it or not?
In another world, what if a different power let him foresee the future? Learn it or not?
And in yet another, what if it granted immortality?
