Sims Gaining Cooking Skill Way Too Fast

The sims in the currently save I'm playing mastered cooking absurdly fast. One sim got to level 7 one day and the next day she mastered the skill, and she hadn't cooked any meals in between the one that got her to level 7 and the one that mastered the skill. And my other sim has just made maybe 5 meals total and he just mastered the cooking skill, too.

The first sim has the practice makes perfect trait and the second has the genius trait, but I don't know why either of those would speed up the cooking skill that much. The practice makes perfect sim is moving more quickly up the writing skill than normal sims, but not in an extreme way. And my sims live on the Crow's Perch lot in Ravenwood but there are no lot traits. 

The cooking skill is the only skill I've noticed this issue with, and if it's just that one it's no big deal, but I would rather my sims work for their skills than just master them right away. 

I play the sims 4 on PC, and it's up to date with the April 30th update. I don't use mods or cc.