Designers love to get their mitts on a logo but dread the thought of building, let alone writing the guidelines to ensure an identity's consistent use – more often then not, the designer as author is usually the first to figure out how to violate the sacred covenant of the brand bible.
Have I designed logos, identity systems and written strict brand guidelines? Yes. Have I been tempted to hire an attorney to write a disclaimer excluding me from any obligation to adhere to the aforementioned guidelines? Oh, yea. Having failed to obtain a single legal disclaimer, am I the first to find a way to stretch the brand guidelines? You bet.
In the end, sustaining a relevant and adaptable identity is a balancing act between elasticity, patience and compliance.