I use one and wouldn’t go without. Not so much on jepps because it’s usually a rudimentary line or a note. I’ll just scribble with my finger.

Our releases are digital so I use it for all sorts of highlighting/annotations/notes and it works great for that.

Not sure what legal reason though prevents us from marking up the jepp enroute map however. That’s one place I’d like to mark information, especially for longer flights. Anyone know a way how that I’m missing?