I have been using a safety razor for shaving my face for a few years, now I just have a beard and don't shave anymore apart from shaping the beard.

But I do have to shave my head and I just can't figure out how to use a safety razor or straight razor for that. I keep cutting myself. The margins seems to be quite narrow and boy does your head bleed if you cut it...so I am stuck with cartridge razors which actually works really well. Just means spending more money and dealing with clogging.