Mower just serviced, brand new gator blades, still missing blades of grass help?

So I do a ton of mowing for several people using a cub cadet sc500z . I keep running into a issue where a matter what I do it leaves several uncut single blades of grass. Even with new blades, serviced everythIng, mulching, going slow, and overlapping rows. Is this normal?

I live in Iowa as well