The overhead is no more than swapping out the cards in the wallet every 3 months and try to remember what the categories are. That's not even necessarily if you regularly use digital payments (and of course if the merchants support that).

(And I believe most people never hit that $1500 cap in specific category. If you do, like, spending $500 on restaurant/Amazon/Costco a month is like nothing to you, ignore everything I say)

I'd say the overhead is much much lower than things like "digital coupons" offered by grocery stores -- those are truly aimed at low income shoppers who are willing to spend time doing that.