The best I can describe my reluctance to write directly onto my calendar pages is a fear of commitment. What if my schedule changes and I've already written it down in ink? Sure, I can simply cross through it or cover it with a sticker, I suppose. But I was looking for something a bit less permanent, yet still allow me to archive the pages.
I had been using Frixion pens, which are great. However, I began to worry that my writing would disappear as the outdoor temperature was already beginning to creep towards 90 degrees.
My next experiment was using thin washi tape. I tried color-coding them to distinguish between each family member's schedule, events i.e. birthdays and holidays, and important notations. I found it's really not my thing. I prefer simplicity and would rather not lug around extra pens with me.
Then I found my answer! These removable white labels are the perfect size for my handwriting. I can move them around from one day to another, discard any that become irrelevant, and if I make a spelling or spacial mistake, I can just re-do it. Plus, the ink never bleeds through the pages and the labels are thin so they don't add bulk.
It's one more bit of planner peace.