WTIS,
My interpretation of 5.3.2.3 is that your referenced "may be returned" to the holding oven, applies to electrodes that are originally placed in the oven immediately after the container is opened, as well as electrodes that were already in the oven prior to the purchase of more electrodes, i.e., a specific number of those electrodes are removed from the oven. If, at close to the 4 hour mark, not all of them are used, the remainder are placed back into the oven, on a different, designated shelf, or an entirely separate oven. Years ago part of my job was to sign out and collect electrodes. We had two ovens. One day, I would issue rods from oven 1 and put any unused/returned rods in oven 2. The next day I would issue rods from oven 2 and put any unused/returned rods in oven 1. If a welder was issued say, 24 rods, at the 4 hour mark, he'd better turn in 24 stubs or a combination of unused rods and stubs that totaled 24.
never put them in the same oven I removed them from that day.