When telling people around me I have #ADHD a common reaction is "But you've always had good grades in school/uni"
So let me walk you through my (sadly common) exam prep: I forgot that I had an exam today. It would pop into my head multiple times last week only to go to the "I do this later" mental to do list. Until last night, when my lab partner texted me asking a question about the material.
And I just went to bed, because oh, the exam is only at 9 am, so I can just study on my way there.