Me, too. but it took a lot of practice to be able to do it! I also sprayed the back of my ruler with basting spray so that it 'grips' the fabric and doesn't shift. At first the back of the ruler was too sticky, but after a little gentle buffing with a scrap of fabric, the 'sticky' is now perfect.
I have the slotted rulers, use them occasionally, too, but not for cutting strips.