Grids are an invisible foundation that structure the websites we develop and design. This invisible foundation makes it possible for rapid development, concise code, and a much more organized layout. Of course you're not obligated to use a grid, and grid-less websites are fine if the random structure is intended, however, if avoidance of a CSS grid is due to lack of planning, then users will be able to pick up on that at an instant. Once you've defined the elements you're going to embed into your layout, then experimenting with a variety of grids is encouraged. Simply because experimentation and curiosity will allow you to find out which grid systems work best for you and your projects.