I have a sharpener and I like it.

I purchased the TrueSharp Power Rotary Blade Sharpener and it does a great job. I always have a sharp blade now. They say it is more dangerous to cut with a dull knife than a sharp one. I think the same thing holds true for rotary blades. And I know it makes a difference in my accuracy.

This isn't about sharpening but thru experience I've learned that a dull blade will damage you cutting mat more than a sharp blade., Think it is because you exert more pressure. Better to trash the blade. I do turn over but when it fails to cut all the way thru ......discard.