Stretching the body is good when the purpose is exercise.
When lifting a heavy object or when engaged in combat, stretching in not a good idea.

The problem with stretching at the wrong time is that it puts stress on the body, reduces stability and prevents freedom of movement.
A stretched joint cannot rotate and turn comfortably.
It is not relaxed.
It is prone to injury.

The internal arts never advocate stretching in everyday life or combat.
The joints remain free and loose, heavy and dropped.