LightFlicker.cs

using UnityEngine;

// Usage: add to a light, specify 6-10 intervals. For a rapidly flickering light, use very short 
// intervals (e.g. 0.01 - 0.3); for a horror-esque feel, use a combination of long and short intervals,
// e.g. [2.1, 0.1, 0.1, 0.2, 0.1, 0.2] for a light that flickers every 2-ish seconds.
public class LightFlicker : MonoBehaviour
{
    public float[] intervals = new float[1];
    private Light light;
    private float elapsed = 0f;
    private int index = 0;

    private void Start() {
        this.light = GetComponent<Light>();
    }

    // Update is called once per frame
    void Update()
    {
        elapsed += Time.deltaTime;
        if (elapsed > intervals[index]) {
            elapsed -= intervals[index];
            light.enabled = !light.enabled;

            index++;
            if (index >= intervals.Length) {
                index = 0;
            }
        }
    }
}