my answer is yes to a list, yes and no about sticking to it, and i rarely remember to use coupons - but i'll say sometimes.
i get a list, my marching orders, from dw.
i do my best to fulfill that list, but as i'm picking up the ordinance, i'll grab stuff on sale, stuff i want to make or have seen a good recipe for, and just other stuff to fill my pantry and fridge. (just to 'splain again, we have a 2 family house that we live throughout, so dw has her own kitchen, and i have mine).
i use a shopper's saver's card in all of the supermarkets that i frequent, so it's like having a coupon for whatever's on sale. occasionally, i'll remember to bring extra coupons received in the mail or by email, or from a previous checkout, but i usually forget that i had them until i've gotten back in the car.