I often make a grocery list before shopping. First of all, making a grocery list helps me plan my shopping in advance. Then it can also save my time doing unnecessary shopping. When shopping with a list, I avoid buying things that are not really needed. In this way, I waste less money.
However, sometimes it is just great fun to shop without a list. One can just enjoy strolling around shops and supermarkets and buying things here and there, or even having a spontaneous walk. Even though you might spend some time and money, you should feel more relaxed after that.