At the soul of architecture is the search for perfect solutions to small and large problems. The rolls of yellow "trace" architects use is a metaphor for that constant search. We sketch quickly overlaying drawing upon drawing refining and exploring ideas until the solution reveals itself.
At one time we ordered rolls in quantity and went through it quickly. Now that we have moved to electronic drawings, we use less and we conduct the search using computers. I do believe hand drawings engage the mind in a different way than drawing with a mouse. Now when I pick up a pen or pencil to draw by hand, the pleasures of hand drawing immediately come back. Whatever the means, it is only a means. At Mock/Wallace, we use whatever produces the best results.