On which font is it difficult to practice quickly?

From the point of view of practicing calligraphy, regular script has a fast foundation, but its practicality is slightly inferior to running script! However, it is difficult to get started with running script, so it doesn't matter if you have a certain foundation of regular script. You can choose some regular script copybooks or copybooks that are easy to transfer to other languages (unlike Liu Gongquan's Tangren), and you can get started quickly (it will be better if you have a certain foundation), such as: Preface to the Holy Teaching by Bei and Zhu, Huadu Temple and Yu Shinan. Because there are only five strokes in the whole spelling, it is also called "Zhao Zichang and Zhao", which is the main line of learning books called "Ou, Qi, Liu and Zhao" in later generations, but Liu Zi had better not learn, but it is difficult to transform! The above personal experience and experience of learning books are for your reference! Wish you success!