I also plan a week in advance (how else would I know what to buy at the store when I go on Sunday night?).
Things do change but for the most part I know what nights (now that I'm off the road) that I'm going to be home vs out late doing something like playing poker or headed out for a weekend trip.
During the perfect week I make something big on Monday night that I can eat a few more times during the week for lunches (Soup/stew is good this time of year to do).