I've been thinking about using them more after seeing a model that used them quite effectively.

1. Does anyone use them often in their day to day design activities?

2. What are the cons to using them?

3. What are the pros to using them?

Our company has recently picked up Matt Lombard's 3 books (Parts, Assemblies, and Administration) and sketch contours aren't recommended except for quick and dirty concepts. Are the situations where they are useful few and far between?