Changing behaviors requires a constant, metered stream of information that incessantly rains down on employees over a long period of time. And, it needs to be initiated with sufficient energy to convey the sense of top management commitment to the outcome. Like marketing a new service to consumers, changing behaviors can leverage what we know about successful marketing campaigns. You can try to emulate television's aspirin ads and run the same message until users are irritated, but we don't recommend it. On the other hand, if you change messages too often you don't really get the benefit from reaching people so busy they don't get the first appearance.
Experience suggests that most companies can benefit from updating messages on a bimonthly cycle.
Of course, your own experience may vary from this nominal, but we'll assume that period for the rest of this discussion. If you notice, the same advertisement for the same product will appear in the same newspaper or periodical for several weeks to several months at a time. Properly done, things that happen in the fifth or sixth show in a series will be entirely consistent with things that the viewer remembers from the premiere show. With an arc, the continuity of the relationship between the characters an the audience is maintained, despite the hours and days between episodes. It's unique for each organization.