I'm all for designing for walkability, but this is a case study in failing to understand audiences. If you make this not just a possibility but a requirement of walkable cities, many people won't want to live in your "walkable" cities at all.
There are much better arguments possible here. For instance, you could promote CSAs for regularly delivered farm-fresh produce, or establish efficient grocery delivery services that use one vehicle to deliver to many many customers, or other potential options that don't involve regular car trips for grocery shopping and don't involve spending an appreciable fraction of your day shopping.
if you're concerned about how your time is spent, i think you're missing a fundamental piece of the puzzle: how much time you spend driving. you could end up saving an enormous amount of time while still going out to shop more if you cut out driving and reduce the scope of your trips.
Nope, weekly trip to the store minimizes all of the issues.
I live in a relatively small city with a pedestrian zone "historic center", and all of the larger...ish shopping centers are outside the city center, and larger stores are on the 'edge' of the city. Both the stores and restaurants in the city center are tourist-based and so are many residential properties that are now just airbnbs causing the housing crisis to be even worse. On a rainy january afternoon (so, last week for us), the city center is dead. No toursts, noone goes there to shop, since you can go futher out with a car, noone goes there to walk around, since it's raining, so it's just a few people that work there during the day and not even them in the afternoon. I mean.. why would you go to shop there, if you can drive to the edge of the city, where you can park without issues, buy stuff and drive it home?