One of the popular washi tape uses is to decorate a journal. It can also be a diary or a planner. You can tape a journal page left and right, top and bottom, making it a framed page.
Or, you can use masking tapes to mark important meetings, appointments, calls, etc., on the diary.
The lovely washi tapes make the journal fun and beautiful, even if you are the only one who sees it.
I collect several different notebooks, planners, diaries, and journals. They could be just store-bought, given by someone, or complimentary copies.
I’m not sure what to do with them because one or two planners are good enough for the year. But I always imagine I’ve tons of appointments/ideas/things to fill in the blank pages.