Can Yu Can friends only put pen to paper instead of using seals in their calligraphy?

Can Yu Can friends only put pen to paper instead of using seals in their calligraphy? Yu Youren, 1879—— 1964, a native of Jingyang. China's modern statesman, educator and calligrapher, especially his calligraphy, had a great influence on later generations. Very rare, you can shoot. His cursive work "Man Jiang Hong" was sold for 1.725 million yuan.