I understand that 3 times the medical bills is a fair settlement in a small accident case is this true?

Not necessarily. There was a time, many years ago, when insurance companies regularly employed a "multiplier" of medical damages to reach a settlement amount. That is no longer true, for many reasons, including that often medical bills can no longer be reimbursed in many auto accident cases. There is no real "formula" for determining what is a fair settlement, it really depends upon the nature of a person's injuries.