NEVER cut fabric on the fold for these reasons:
The garment pieces are cut from right-to-left if right-handed, left-to-right if left-handed
Block out (industrial jargon meaning to cut around the garment piece so it can be separated from the rest of the layout) one of the pieces, then turn the block as you cut so that you continually cut from right–to-left. Slide the shears on the table as you cut. This gives momentum and speeds the cutting.