There's something unsettling about having two pages left to fill in a lab notebook. It feels like something strange is about to happen, even though I have a new lab notebook ready to replace this one. There'll be a slight nuisance while I have to carry both (to refer back to the last few days of notes), but that's temporary. Still, actually filling a notebook seems like arriving at the edge of the world after a long journey.
I've gone through a lot of notebooks over the years, but have little experience filling them. Most were abandoned midway, when the course finished or the project was complete (or cancelled). More often than not, 2/3rds of any given notebook is empty, even after I learned the trick of turning a spiral notebook over and writing from the back forward so that one notebook can be used to two classes (or two projects, or one project plus personal notes).
Pens are another matter. With pens, you rarely see the end coming.