The chest is the placement with the most symmetry to respect and the least room for a mistake, because the eye reads both sides against each other automatically.
It is also, with the ribs and the sternum, among the sharpest places on the body to sit through. That is worth knowing before you book a full day.
For most people the ribs and the sternum are the worst place on the body: thin skin directly over bone, and it moves every time you breathe. Nobody sits through it comfortably.
One pec, often yes. A full chest across the sternum is more than one day for almost anyone, both for the work and for what you can physically sit through.
No, but it has to be deliberate. An asymmetric chest piece works when it is clearly a choice and looks like a mistake when it is not.
They hold well as long as they stay out of the sun. Chests and shoulders get far more sun exposure than the parts people usually worry about.
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