Only a small percentage of American watches (or Swiss watches for the North American market) were cased at the factories prior to the mid-1920's (even then, uncased movements were furnished to the trade at least until the 1960's). Most watch companies just made movements (the "works") in industry standard sizes. These were shipped to jobbers, distributors and retailers in
various tins and other containers. The case companies made cases in those same sizes. The practice at that time was to go to a jeweler, select the quality of the movement and then pick out the desired style and quality of case. The jeweler would then fit the movement to the case in a matter of moments.