At present, the use of double hook pen method accounts for the majority. I think this is mainly due to the habit of calligraphers when they first came into contact with calligraphy practice. It does not mean that double hooks are better than single hooks, or which one is more orthodox. Single hook is more free and easy to write in cursive script; Double hook is more resolute and more suitable for regular script. Mainly a habit.
Single hook method is suitable for writing small characters, while double hook method is more stable for writing large characters. Everyone has different writing habits, as long as they can write good words that suit them.
Many people in history have had a lot of writing experience, and there is no consistent conclusion about single hook and double hook. In my opinion, the height of calligraphy has nothing to do with the method of writing, so don't be too persistent.
Figure 1 is a single hook, and Figure 2 is a double hook.