A thousand birds or a spiral pill?
Sasuke has mastered the morphological changes and attribute changes when he first learned Thousand Birds. After all, Kaname Chidori changed chakra's attributes into ray attributes, then changed the shape, and finally used high-speed movement to increase the endurance of injury. Therefore, when Sasuke first learned Thousand Birds, there were two kinds of chakra control: morphological change and attribute change.
? However, although there are more ways to control the seemingly thousands of birds in chakra. In fact, at this time, a thousand birds are not as powerful as spiral pills. Because Sasuke and Naruto once fought on the roof of Konoha Hospital after Yarrow defeated bijuu. Chiba used by Sasuke and spiral pills used by Naruto are both new and the conditions are the same. However, after Kakashi deviated from the attack trajectory, Naruto's attack made a big hole, while Sasuke's Chiba only made a small hole.
In other words, when learning spiral pills and birds, spiral pills are better than birds. Because the rotation of the spiral pill will have a powerful destructive power after hitting the enemy, and the thousand birds will only play a role when they hit the enemy's key. Then there is the strength comparison between Naruto and Sasuke after upgrading the spirit body and Chiba. When we met at Oromo base, Sasuke was already very strong. So I think a thousand birds are not born as spiral pills.