You can quickly create content on the flat plan without needing it to be assigned to a client.
NOTE: This method provides a handy way to produce content quickly. However, as these bookings are created for one issue only, they will not be reproduced to your next flat plan when you duplicate your flat plan. You may wish to create a "dummy client" for regular house articles such as "editor's page" or "puzzles". This would enable you to create an ongoing content booking which would be reproduced when you duplicate a flat plan.