Bill, from what was explained at the workshop the over cuts are 45 degrees to the face of the mat. You can take a rounded burnishing tool and rub it the length of the over cut to close it up. Closing the cut up like that makes it 80 to 90 percent less visible. It's effective enough that you have to get up close and look for it to see it. The "self healing" mats were not mentioned at the workshop. We asked the question on how long the blade will last. The answer is it varies. It depends on how thick the mats are, the hardness of the mat (Some mats are softer than others), how many cuts are made on each mat, etc. When a blade starts dragging through the cut it's time to change it. You learn it by experience. I got the impression that a blade should last for more than a few mats. It was also pointed out that on the bevel cuter tool the blade should always be retracted after each cut is finished. If you don't two things can happen, you can cut your self and setting the tool down on the blade point will dull it very quickly causing ragged or torn cuts or the point can break off causing the same problems. Also understand, like you, I have not cut any mats. I am just repeating what I've been told at the workshop and in watched the demonstrations. I was impressed with mats that were cut and with the instructions that were given. Hope this helps.