I'm a huge believer in design walls -- which of course are so much more than just a wall, but a way of life.
Early in my own experience as a quiltmaker I took a workshop in which we each brought some batting and taped it to the vast cinderblock walls of a basement room in a convention center. Until then I had never heard of a design wall, or known that batting over a firm surface is "sticky" enough to let you put fabric up without pins. Nor had I realized the huge difference between spreading your work out on the floor or the bed and actually getting to step back and see it head-on from a distance.
I think the design wall for a quilter is akin to the word processor for a writer (and I speak with the authority of one who did lots of quilting and writing without benefit of these tools). With the tool comes the ability to refine and fine-tune your work far more easily than you could ever do without the tool. With just a typewriter, editing and rewriting quickly became a mess of cross-outs, insertions, type-overs and cut-and-paste. Pretty soon you said to yourself "to heck with this, it's good enough,I'm done." And often that was too soon. But with a word processor, every time you revise or rewrite the work is right there in front of you, clean, neat, readable.
The same thing happens when you look at your work on a design wall. You can arrange and rearrange quickly and keep working at it till you get it right. No more climbing up and down on a chair to try to get a long view; no more walking on top of your spread-out fabrics to get to that spot in the middle.
No matter what kind of workshop I teach I ask that people have design walls. Many times the students are having their first encounter with vertical display of their work in progress, and as a result are having their first encounter with the ability to audition fabrics and colors, to fine tune, to make decisions as they work (instead of committing to a design in advance and then simply executing it, good or bad).
On occasion I have been fortunate enough to have workshops in space with pre-existing design walls, big expanses that can be pinned into. I used to teach occasionally at a quilt shop that had several big 4x8 foot panels that could be hauled out and propped against the walls, and once I persuaded a local quilt group in advance of the workshop to buy a dozen panels that could be used again and again.
More frequently, people will bring a big piece of batting and hope they can find a wall space to hang it on, or bring their own smaller panels of cardboard or foamcore and hope they can find a place to prop them up. But often the design boards end up propped on the floor, not easily visible, not easily fussed with (especially for us aging ladies whose knees and hips don't like us to work at ankle-level).
On the way to a workshop I always fuss and fret over whether there will be adequate design wall capability, so it was with great delight that I stepped into the studio in Ft. Myers. There were lots of easels in the room because it's most frequently used by painters. The easels turned out to be perfect places to park medium-size design boards up at eye level, visible while you were sitting at your sewing machine, and even more visible if you needed to step across the room for a longer view.
A few people put up batting for their design walls, and that worked just fine, but the usable wall space was limited, so the easels saved the day.