"Beast Taming" was a skill Wang Sheng had acquired early on. Occasionally petting Da Bai could enhance his progress, so it increased rapidly.
He achieved a Breakthrough in no time, and although he petted Da Bai less frequently afterward, the progress slowly continued.
Eventually, both Da Bai and Yun Xiao fell into a long silence that lasted a year or two, focusing on their evolution.
Meanwhile, he busied himself with cultivating more and more skills, often neglecting Beast Taming. He barely attended to Da Bai and Yun Xiao and later learned Sword Flight, which made Da Bai unnecessary for traveling. Thus, the progress in "Beast Taming" gradually came to a halt.
Now, having reached Breakthrough three times, Wang Sheng himself was initially bewildered.
But soon, he realized why.
This time, using Da Bai as transportation counted as him taming Da Bai, so the progress bar was actually continuously growing.
That's why there was this sudden Breakthrough.