It's really no different than Jabra, Kumadori and Fukurou not being introduced until Enies Lobby.
We knew about CP9 in Water 7 and met Lucci, Bleuno, Kaku, and Kalifa first then saved the rest for Enies Lobby. Just like we learned about the Tobi Roppo in Wano with Drake and Page One.
If anything its less random because we knew there were 6 members to begin with, so we anticipated seeing the remaining 4 members.
We knew about CP9 in Water 7 and met Lucci, Bleuno, Kaku, and Kalifa first then saved the rest for Enies Lobby. Just like we learned about the Tobi Roppo in Wano with Drake and Page One.
If anything its less random because we knew there were 6 members to begin with, so we anticipated seeing the remaining 4 members.
Arc endings have never been oda's strength imho.
My top 5 arcs still remain:
1) Water 7
2) Sabaody
3) Jaya
4) Zou
5) Skypiea