I used to be a kitchen trainer at McDs in high school, one of my trainees got fired on her first day without me because she couldn’t remember what the different types of meat were. This was not only after spending my last 4 hours with her running through it repeatedly, but even directly after someone told her what they were she wouldn’t be able to point any of them out. I felt kinda bad because she was otherwise really nice, but it really was impossible to get her to retain any information.