Yeah while I've pulled a few on progressive events it is rare from what I've seen and heard from others experiences.
Since you can see even with Epics how quickly you max the progressive chance for those and still can take forever for that champion to get pulled. There are far too many champions and that progressive chance is so low. Which is normally you have a 0.02% chance base chance for a specific Epic and then 25x makes you have 0.8% chance. Not even a 1% chance to get the epic you want. The progressive system would be so much better if instead of 15x, 20x, 25x it was +15%, +20%, +25%. Then it would change from 0.02% to 15.02%, then 20.02%, then 25.02%. Still not guaranteed but will make it a lot more likely when pulling on these banners.
There are some other gatcha games I've played in the past that I like their pulling system a lot more for progressive style. Their mercy is a lot lower for their legendaries sitting at 90 pulls for guarantee and increasing chance starting around 75. If you are pulling on a banner aka our progressive style then if you don't get the champion the first summon of a legendary pulling on the banner the next time you hit a champion it is guaranteed that you get it. So at most you have to use 180 pulls but you know that you will get it. That game though doesn't have pvp and is more of an action based hero collector instead of an afk battler hero collector. Looking at their revenue numbers comparing the two for reporting revenue in 2024 they made $4.7billion and Plarium made $613million.