My current favourite new discovery is the three markers in the Leuchtturm1917 Bullet Journal. I think that just having one is barley more useful than having none, because I usually want to mark and keep track of more than one thing; I do for example use one to keep track of the next free page and another one to show how long I have come in transcribing used pages in my long form writing notebook.
The way I use the three markers is in my journal. The first one is used to mark the first page with un competed tasks,. The second is used to show the page I was working on last time I closed the book. And the third is used to show the first unused page.
Having three instead of one makes it possible to navigate it so much faster than what I would have been able to if I only had one marker. I’m not sure if having three instead of two is that different, but two instead of one is a game changer.