if your mmr is high you can skip from division 5 to division 3, division 4 to division 2, division 3 to division 1.
you can't skip from a division 2 straight in to the next tier though.
it means maintaining a sustained extraordinarily high win rate though, when I ranked my second account I went from g2 to g1 and then p5 to p3 but I guess since I wasn't able to maintain a high enough win rate (i failed one or two promo series in plat) I wasn't able to skip from p3 to p1 and had to just grind that normally, though my lp gains were like +28 so it was pretty quick.