Reasonably exhaustive Thursday in Common Pleas

What does it mean to complete a "reasonably exhaustive search," as required by one of the five prongs of the Genealogical Proof Standard? When this was debated last year on the Association of Professional Genealogists mailing list, one working definition came up: if you described your search, and if a top genealogist said, "But did you look at X?", and you hadn't looked at X, then your search was not reasonably exhaustive. Even though this reminded me of the joke that my dad, a math teacher, liked to tell ("Mathematics is what mathematicians do"), it actually makes some kind of sense.

Hoosier researchers can add an obscure Indiana court to the list of things to look at. From 1853 to 1873 Indiana counties had, in addition to the circuit courts that persist to this day, a Court of Common Pleas, which had jurisdiction over probate cases as well as law and equity cases and criminal matters (except felonies and debts over $1,000). (A brief accessible description is on page 377 of the History of St. Joseph County, Indiana, at Google Book Search, although I think its description of the jurisdiction is incomplete.) So if you know your Indiana research target was in court during the decades surrounding the Civil War -- or if you hope he or she was because you need the records, any records -- your search is not going to be reasonably exhaustive until you ask too see those order books and case files ("loose papers").

I have seen Common Pleas order books interfiled with Circuit Court books in clerk's offices that were otherwise models of conscientious record maintenance and preservation. From one decade to the next, does anyone know to ask for them? They may be even more neglected than mortgage books (as compared to deed books).