Recently I had a project situation where my client needed updated drawings in about an hours time from when I saw the email. I needed to create a new family for structural outriggers on a deck, and had two different sizes to make. If I had more time I usually would make a parametric family that could essentially be any size.
Since I didn't have the time, I used the Yes/No parameter and assigned it to the Visible family parameter to quickly make the two sizes I needed for this particular situation.