Just wanted to bring to your attention that Mentor's Vern Wnek has recently written an informative article for Printed Circuit Design & Fab on the pros and cons of using constraints. The article, titled "Using Constraints to Make PCB Layout Easier," also provides a step-by-step procedure for effective constraint entry.
Check it out, and let us know what you think!
If anyone wants to have me present to your design group my Design methodologies and CES setups please let me know. I have been onsite to approximately 40 company sites or more explaining how to use CES to your design teams advantage.