Meh, I just cut off a piece about as big as I think I need and stuff it in there. I cut a piece well larger than the filter basket circumference, lay it over the top and push it down in the middle. Protip, as long as you have the scissors out, cut a bunch of them. Then you're (well, I'm) a lot more likely to change it instead of putting it off another day or three.
IMO, that works best. Rolling it is uses more (I think) and layering it, well, that probably also uses more, but it's a lot more work too.
The only advantage I can see for making layers is that instead of changing it, you can just remove the top layer.
FWIW, at least in my system, the water flows over the edge of the basket (as opposed to flooding that section, so the only part that really gets all that dirty is the edge facing where the water comes in.