It really takes a lot of time to shave the whole body; or at least it has to be done slowly and carefully.
Last time I shaved I was sort of in a hurry and got scratches in my body like the one in the pictures. They itch later but don’t hurt much, but definitely look ugly!
If you are shaving your whole body, take it slowly; consider spending about one hour in the shower to complete the task without hurting yourself. Also, make sure you are sliding the blades in complete contact with your skin. I know is difficult, specially when shaving the back and sides; and takes lot of practice, but if the blades go in an angle, they create these scratches.
But mostly, don’t make the mistake I did and do things in a hurry…take your time!