Not sure if it's still the case, but FEH used to not have pity and had E7 chances. On top of that, every banner had every unit in the game at the same chance. And when they introduced pity, any 5 star reset the pity, not the banner unit
Trust me wulf, e7 isn't the only one that doesn't have a guaranteer 4 star in 10 pulls. Look at summoners wars, i played for 8 years and do you know how many ml5 i've got? 0. never going back to that ever again.
I always go for ml summon if 100 bms and Bonus and never had that much luck like you. BtwJenazad streamed a 800 GBMs summon race.... horrible And: not a single arti to me.... you are such a lucksack And a hint. SG do not know how coding of RNG (heuristics) has to be done. If you get 10x 3* you have to wait a minute or you get bad luck again. Same if you get 4", then hurry, the chances are best now (I play longer thsn you btw)