To put it simply, flying white is unlikely to appear on regular script, because when writing regular script, the pen and ink are full, and writing a word can be polished several times, while running script and cursive script need to be completed in one stroke, so the writing speed is fast, and it is easy to appear flying white at the turning point of strokes and the last stroke of a word.
The blank space in freehand brushwork can highlight the main body of the painting, so that the painting will not be chaotic, and at the same time, it can also make the viewer daydream infinitely.
The above is my own understanding of flying white space, I hope it will be useful to you.