That’s just math lol. Featured is 1.2% I believe, so probability of NOT getting a featured 5* is 98.8%.
If you calculate the cumulative probability, or 1-P(not getting featured legendary)^pulls or 1-(0.988)^pulls, you’ll see that when pulls = 250, you already have a 95% probability of getting at least one featured legendary, and at 300 pulls that rises to 97%.
Obviously some get unlucky and fall into that 3% tail end, and some get extremely lucky and fall into the 3% on the opposite end of the probability curve.