One can read the WCAG 2.0 Guidelines from end to end in an afternoon. It is not an easy read, but it is doable. The same cannot be said of the Techniques or Understanding documents. Taken as documents for end to end reading, they are nearly impossible. The key misunderstanding here is that someone would ever need to read either document from end to end. The Understanding and Techniques documents are intended to be an indexed compendia of long descriptions for the WCAG 2.0 guidelines and success criteria. They are only meant to be read as needed to comprehend or implement a guideline or success criterion.
Taken as a whole, the content of WCAG 2.0 is a tree. The root WCAG Guideline document is partitioned locally into Guidelines. The Guidelines are split into Success Criteria, and each success criterion points to an informative description in the Understanding document and a collection of tested sufficient coding techniques in the Techniques document. This organization enables using a large body of essential concepts to be organized in a operationally manageable format. One can read the Guidelines for a precise description of user needs that must be met to serve users with disabilities. For clarity one may drop to the section of the Understanding Document for a given criterion to find an informative user oriented description of the formal language for the given criterion. When one implements a criterion, the Techniques provide precise tested coding strategies that meet criteria in ways that are known to work. Once an implementer is at the techniques level every case of the success criterion is addressed and appropriate solutions are given.
The Understanding and Techniques documents do contain a lot of information compared to the Guidelines. This is not surprising. The Guidelines document is the root, and Understanding and Techniques documents are the frontier of a tree information structure. Trees always fan out. That is how we organize very large quantities of data we don't intend to read sequentially. The organization of the WCAG 2.0 documents allows a manager or implementer to find the exact information they want quickly even though the total base of information is extensive.