Simultaneously engraving dozens of documents isn't because magic can only achieve this much, but because Zhao Guang's own spiritual tolerance has reached its limit. This is done externally; the clones in Wisdom Tower cannot assist.
If the quantity increases, his spiritual power won't be able to bear it.
After all, multitasking is not easy. If it weren't for Zhao Guang's special rules, he would have already adapted to this method. If it were someone else, even with equally strong spiritual power, managing to write twenty documents simultaneously would be considered good.
And the upper limit of this magic is evidently not that low, as Zhao Guang initially set it to write several hundred documents at once.
Zhao Guang himself cannot reach the magic's upper limit, and his spiritual drain is rapid. Not long after, he was exhausted and had to rest. After several days back and forth, Zhao Guang finally managed to accomplish what he had envisioned.
