I spend about an hour a week at the grocery store. I bring my 3-year-old with me, and she brings her own little shopping cart and helps pick out what we buy. I think of it as a fun bonding activity and an opportunity for her to get exposure to a wide variety of food, rather than a tedious chore to be optimized. Sometimes she picks out weird fruits and then refuses to eat them, but overall I think it has helped broaden her food horizons.