RandomHighlight.cs

using System.Collections.Generic;
using UnityEngine;
using Random = UnityEngine.Random;

public enum SwitchHighlightMode
{
    Random,
    InOrder //Loop
}

public class RandomHighlight : MonoBehaviour
{
    public Material HighlightOnMaterial;
    public Material HighlightOffMaterial;
    
    public SwitchHighlightMode HighlightMode;

    private List<Renderer> Switches;
    private int switchCount;
    private int CurrentHighlightedSwitchId = 0;

    private float NextHighlightDuration = 0.8f;

    private void Start()
    {
        SetSwitches(transform); //1
    }

    public void SetSwitches(Transform SwitchParent)
    {
        Switches = new List<Renderer>();

        switchCount = SwitchParent.childCount;
        
        for (int i = 0; i <switchCount; i++)
        {
            Switches.Add(SwitchParent.GetChild(i).GetComponent<Renderer>());
            Switches[i].material = HighlightOffMaterial;
        }
        
        ChangeTheHighlightedSwitch();

    }

    void ChangeTheHighlightedSwitch()
    {
        Switches[CurrentHighlightedSwitchId].material = HighlightOffMaterial;

        switch (HighlightMode)
        {
            case SwitchHighlightMode.InOrder:
                CurrentHighlightedSwitchId = (CurrentHighlightedSwitchId + 1) % switchCount;
                break;
            case SwitchHighlightMode.Random:
                CurrentHighlightedSwitchId = Random.Range(0, switchCount);
                break;
        }

        Switches[CurrentHighlightedSwitchId].material = HighlightOnMaterial;
        
        Invoke("ChangeTheHighlightedSwitch", NextHighlightDuration);

        // Invoke("ChangeTheSource",Random.Range(nextMinDur,nextMaxDur));

    }
}