I have a small 3 ring binder in which I have at various times put in commercial refill pages and at times carefully made DIY pages like the ones in this thread. Here is the process I use today.
1. I take a stack of blank computer printer paper, fold it in half, and cut along the fold.
2. I trim the edges to fit the notebook size.
3. I punch 3 holes in the stack and insert into the notebook.
When I do a dive, I write whatever I feel is important on a blank page. Sometimes I have nearly nothing to say. Other times I have a lot. I use whatever space I need, draw a line at the bottom of the entry, and start the next dive under the line. Sometimes I get 4 dives per page. When I have a lot to say, I may only get one dive per page, but that is pretty rare.