Well, it all depends on your business philosophy. So, cutting to the chase - if you want your product to have the best chance of functioning properly and performing reliably throughout it's expected lifetime without bludgeoning your company to death from warranty reparations, liability litigation or a damaged reputation, then you must consider unspecified, as well as, specified wear and tear when you define the product.

1. The intent herein is to outline a list of considerations for the product developer, manager and executive who may not think about the nuances of product vulnerabilities that are many times 'out of sight' as a product is defined.
   
   
2. This article is not intended to be a treatise on the standards for, nor the methodologies of, product environmental testing. For this type of information, search the Internet for:
   • "Shake Rattle and Roll' or "Shake and Bake" testing
   • STRIFE, Stress, Aging or Life testing
   • HALT Testing (Highly Accelerated Life Testing) and HASS Testing (Highly Accelerated Stress Screening)
   There are also many organizations and standards, which spell out test criteria and testing details, e.g.:
   • American Society for Testing and Materials (ASTM); http://www.astm.org/
   • Degrees of protection provided by enclosures IEC 60529; http://www.techstreet.com/cgi-bin/detail?product_id=861222
   • Network Equipment-Building System (NEBS) Requirements: Physical Protection; Telecordia GR-63-CORE; http://www.nebs-faq.com/
   And there are various test facilities, which are able to test products to these standards, for example:
   • http://www.elliotlabs.com/
   • http://www.environlab.com/
   • http://www.e-labs-inc.com/
   • http://www.garwoodtestlabs.com/