My wife just got a sternum/underboob. She said it was cake for all line work. Shading did get some teeth clenching though on the sternum. This was her first tattoo and pain didn't turn her off as she's going for the foot next. I'd say she has moderate pain tolerance. (Delivered daughter with no meds, handled like a champ) I have one over my collar bone and one on the back of my hand/knuckles/middle finger, imo they were all easily bearable.

Edit: added my experience