Community Tip - Did you get called away in the middle of writing a post? Don't worry you can find your unfinished post later in the Drafts section of your profile page. X
I'm trying to guage best practice for validation effort when installing a Windchill maintenance release (i.e. M050 to M060). Do you run through end to end validation? random samples? Validate customizations?
Do your Functional or System Requirements Specifications for Windchill change? If they do, then Validate those requirements.
If you have customization (workflows, object types etc.) I would think you should validate those also.