Is it useful to shake a pen in Jiuchenggong?

no. The three characteristics of Jiucheng Palace are: the strokes are well-proportioned, the strokes are steady, and the strokes are more calm and restrained. The shaking pen, also known as the "war pen" and "shaking pen", is a brush that moves forward in the running process, so that stippling presents a kind of astringency to achieve the effect of vigorous lines. It doesn't conform to the characteristics of Jiuchenggong calligraphy, so Jiuchenggong didn't use a shaking pen.