Those 5% cashback categories only apply to the first $1500 spent that quarter. Basically if you were to regularly use your discover card you’d instantly hit the cashback cap within a week.
No, I've never hit the cap. I don't spend (for instance) >$1500 on gas in a 3 month period. And these are all purchases I'd be making anyways - why not put them on my Discover card for higher cashback than my "default" card?
