how do i make a pacing system?

i want to have it were somthing happens after said amount of seconds and then reset and repeat. I would like to use this to make a shooting part in my game so that when a tower shoots at an enemy it’s bullets come out with paced and not just like a lazer.

http://answers.unity3d.com/questions/273094/unity3d-timer-request.html

http://answers.unity3d.com/questions/11458/how-to-make-a-timer-in-the-game.html

http://answers.unity3d.com/questions/11939/count-down-timer.html

http://answers.unity3d.com/questions/225213/c-countdown-timer.html

You can achieve that using coroutines:

public float Interval = 2f;
private bool _shooting;

private void SomeMethodCalledWhenEnemyEntersArea() { // for instance OnTriggerEnter
    _shooting = true;
    StartCoroutine(ShootAndWait(Interval));
}

private void SomeMethodCalledWhenEnemyLeavesArea() { // for instance OnTriggerExit
    _shooting = false;
}

IEnumerator ShootAndWait(float interval) {
    while(shooting) {
        Shoot();
        yield return new WaitForSeconds(interval);
    }
}