I have the same problem. I have to check it 3 times, then wait, 3 times again, wait, then 5 times. If I don't do it in that exact order I feel like my alarm won't ever go off.
I also eat certain things in multiples of 5: cereal, Spaghettios, Macaroni, crackers, etc. I only have a few weird habits, but the ones I have are extremely exact in how I do them.