Well it really does not matter so much in a way. Once the grain bed is set the grain will be filtering the wort. I put the slits a touch under half way and about every 1/4 inch. I used a band saw to cut them so the width of the slit was pretty narrow as well.
If you are batch sparging it matters even less. If you are fly sparging the shape and making sure it is a equal amount of slits throughout or evenly spaced matters a bunch
Ughh hung over and I hope it makes sense
