I'm reading Wexler's DD website....Each line is a book....but I'm particularly stuck at one concept which may be easy to answer by most here. QUestion is.... when they describe Doubled Dies...they describe the obverse, the reverse and, in some cases, the 'stages' Does the stage imply a progression in time? Like, for example, on a hypothetical case.... earlier dies will produce certain findings of coins made in January 2017 (stage A) and other findings in coins made in say June 2017 (stage B)??
It is a progression of the Dies life. Stage A would be an early die state Stage B a mid die state etc.
As a die wears in it's useful life, sometimes previously-identifiable things like die scratches wear off. Sometimes a clash appears, and then disappears when they polish it away (creating new die scratches which weren't there previously). So, there's rarely any continuity in the features a given die presents during its' life, and the pickups you use for a given die state - including the strength of the original feature which caused the variety assignment - change almost completely for a later state.