Do you mean shopping without a list? Or, going shopping even when you don’t really need any food in particular? I assume the former.
I go all the time without a list, but I probably should always use a list, because it’s not unusual for me to forget something.
I usually don’t let staple things run out, so if I forget on one shopping trip I can just buy it the next trip and I haven’t gone without. Things like bread, milk, eggs, bread crumbs, lettuce, some sort of fruit, cucumber, carrots, flour, sugar, spices, pasta, rice, frozen vegetables, fresh mushrooms, green beans or zucchini, canned tomatoes, canned beans, spaghetti sauce, and I keep a few frozen dinners for back up.
I haven’t been very creative with my cooking, so I always have a lot of the basics I need to prepare almost anything. Spices, condiments, some canned goods, rice, pastas, etc.
I live one mile from two grocery stores, and there are two others I pass by constantly, and two more beyond that that are near other things I do, so running in to pick up something isn’t a big deal. I also don’t work full time, so I have a lot of free time.