It does. Last EG i tried with 10 gachas and no slayer (this and the fiasco to see N cards in event gacha again), i don't bother to purchase those again.
Not sure how you can try 10 times, and not get a slayer. We both know the chances of getting a slayer go up with each fail. The only thing I can think of is you don't have card reveals to use when the chance reaches 100%.