Feeling waves of sharp pain from her wounds, Unohana treated herself with Kaidō as she asked in an uncertain tone, "Given the endurance of your Sōken and Hakuin, you shouldn't be able to maintain this state for much longer, should you?"
As everyone knew, the more explosive and destructive a move was, the less sustainable it tended to be.
Reiatsu was especially so. It was like using the energy stored within one's own soul as fuel and burning it.
Assuming the total amount did not change, the more intensely it burned, the shorter it could last. Conversely, the less intense the burn, the longer it could be sustained.
Clearly, the mode Allen had displayed, something similar to Shunkō, was an extremely intense state of combustion, consuming far more than most Zanpakuto Bankai.
So in Unohana's eyes, if he could sustain it for over five minutes, he would probably already be nearing his limit.
If he continued any longer, even his soul itself might be burned away completely.
"Hmm! Under normal circumstances, based on the endurance of a soul's Sōken and Hakuin, it would start falling apart after three to five minutes and turn into Reishi that scattered through the air. But when did I ever say my soul was ordinary?" A faintly amused smile appeared on Allen's face.
You must know, his current Death soul had been formed after being reshaped by the Soul-Soul Fruit and the soul energy of tens of millions of alien races, monsters, and beasts.
Its stability and self-repair ability were far beyond anyone's imagination.
If calculated purely in terms of this world's Reiatsu, even the entire Gotei 13 combined, including those fellows from Zero Division, could probably barely match a third of it.
So let alone maintaining this state for a few minutes—even a few