I agree, it depends on the bird. Jezebel is a perfect "shoulder bird" for now, as she hasn't reached maturity yet, she will sit there for hours, and not move.
Lu, is not allowed on my shoulder, he likes to pull my earrings, and I am one who is NOT going to take out my earrings for his convenience, he needs to learn to ignore them, and he hasn't, so no shoulder for him. He also likes to give a nip when I'm not giving him the attention the thinks he's worthy of, and I like my face and ears just the way they are.
Sid, NO WAY he will EVER be on my shoulder! He is very unpredictable and will even sucker you over to his cage for some pets, and after you feel comfy petting him thru the bars, he'll step up onto your fingers and proceed to bite your fingers, while he's standing on them. And he's FAST!!!!
I've been bitten by all 3 of my guys, and they all have a different MO, Jeze will bite you so fast and hard, she's back in her original position before you even realize you're bit, Lu will "test" first, then grind, or he also likes to bite with the side of his beak, and THAT really hurts.
Sid, well, he's a too, and he has 3 pressure points on that beak, opposed to my other 2 fids. Those bottom beaks are really sharp, and it's more of a scissors bite.
Now that I've rambled on and on, (why didn't anyone stop me?
) I'm back to my original statement, it all depends on the birdie.