Kaidou is the only character to share the skies twice and maybe 3 times if we count Shanks 2 years ago, while Shanks can be said 2 times.
In fact, Whitebeard also shared the skies twice, with Roger and Shanks, while Kaidou with Big Mom and Luffy, we can hypothetically insinuate that Shanks and Kaidou shared the skies too, hence the sky division ranking:
1st Place - Kaidou with a total of 2 times could be 3 assuming Kaidou and Shanks shared the skies.
2nd - Place - Whitebeard with a total of 2 times.
3rd - Place - Shanks a total of 2 times, with Whitebeard and hypothetically with Kaidou.
4th and 5th place - Big Mom, Roger and Luffy.