Why? For example, when designing a set of clinical studies, we might base an endpoint on similar studies in the literature, have different variations of the endpoint in different studies, use various analytic methods, etc, all of which is documented in a long series of text documents (see list on the slide below). Likewise for objectives, visits, assessments, inclusion/exclusion criteria, tables, figures, and listings, etc.
Over years, I've developed an approach to organize each design element (and variation thereof) among a set of studies into a spreadsheet. Essentially, the spreadsheet is a map to all of the design elements in a clinical program: instead of having to search through multiple documents for details, it is all in a single spreadsheet. For instance, if the definition of "Metabolic Syndrome" changes in the middle of a program, the design map shows at a glance which studies used which definition.
(NB: My daughter made these drawings)