2. Even with today's prices, storage is a relatively minor expense for professionals working at this level.
3. When material above 4K is used in a serious workflow, it tends to be at the acquisition phase only. In post production, raw files get transcoded to a proxy format (e.g. ProRes 422 Proxy) for editing.
4. In multi-user workflows, media is commonly accessed directly from shared network storage instead of duplicated onto individual machines.
5. Effects work is normally handled on a shot-by-shot basis. Even if they're working on local copies, we're talking mere minutes of raw material, if not seconds.