These cuts were made with the parts printed on standard copy paper, laminated to another sheet of paper, so the thickness is about 0.2- 0.25mm. But our kits often have parts on thicker stock.
This is a circle cut out on 0.5mm paper stock. I used both the 30 degree and the 60 degree paper and got good, consistent cuts. The trick is the first put the cutter on the paper and then adjust the pressure of the blade to prevent burrs on the circle from where the blade first contacts the paper.
I also tried it on 1mm card using the 30 degree blade. As you can see, even after a few passes, the cut did not go all the way through consistently. This was with the blade set at maximum pressure.
However it did cut nearly all the way through, and it was a trivial matter to finish the cut with a hobby knife. The end result was a clean circle and disk.
I give this product a thumbs up, especially now that the center locator is included with the cutter. I'm throwing my compass style cutters that leave a hole in the middle of the part away!