How easily can a bone bruise turn into a stress fracture?

Stress fractures: Are the result of excessive pressure or strss on bone for a prolonged period of time. Not from a single incident of trauma. So if there is no abnormal stress on bone, stress fracture should not occur.

Stress fracture: Often there is cross over, a bone bruise doesnt really turn into a stress fracture but a bone bruise taht still hurts may be reevaluated and upon looking at it a little closer it may be now called a stress fracture.