Personally tried going out this way. Wasn't a shark knife. Old big hunting knife that was super blunt. Basically just slammed it into my wrist in a fit of depressed rage.
It split open my wrist, I could see my muscle, and tendons, a split vein or two. The tendons were sliding in and out of the cut. I only got half of them. It quickly gushed and filled up with blood in a matter of seconds. I sat there and accepted it for about 2 minutes, it was almost a moment of relief, while I cried, kind of the same feeling when cutting.
I cannot remember correctly, however it didn't hurt. It's still numb to this day.
After the two or so minutes. I got a sudden feeling of chilling down my back. I tensed up and began to freak. Put blood all over the house (home alone) as I panicked. Rararaa
Tldr: no it's a shit method. It's hard to lose a hand and die. It's just as hard to take a laceration and die. Especially if someone finds out and calls an ambo or wraps a towel around it. Because that's literally all it takes. A towel, some pressure and you'll do perfectly fine. You'll also give your mind too much to regret or go into full trauma mode.
"Wrists are for girls, I'm slitting my throat."