Many loops to instantiate different prefabs during a given time

Hello, I'm returning to game development studies using Unity, I believe the answer to my question is something simple, but I tried and researched a lot without progress.

I'm trying to create a process to randomly instantiate prefabs that are in an array. For now there are only three levels, each lasts 10 seconds and has different prefabs to be instantiated.

I was able to do this using the Inumerator, however for each level i need to create a new loop. Here's the script:

     private float _levelOneTime = 10f;
     private float _levelTwoTime = 20f;
     private float _levelThreeTime = 30f;
 
     public  GameObject[] _levelPrefabs;
 
     private Coroutine _spawnerCoroutine;
 
     void Start()
     {
         _spawnerCoroutine = StartCoroutine(Spawner());
     }

// Here where the magic happens, I had to use three loops for three different instances.

     IEnumerator Spawner()
     {
         while (Time.timeSinceLevelLoad <= _levelOneTime)
         {
             int randomPrefab = Random.Range(0, 2);   
             Instantiate(_levelPrefabs[randomPrefab], new Vector3(0, 0, 10), Quaternion.identity);
             yield return new WaitForSeconds(5);
         }
         while (Time.timeSinceLevelLoad > _levelOneTime && Time.timeSinceLevelLoad <= _levelTwoTime)
         {
             int randomPrefab = Random.Range(3, 5);
             Instantiate(_levelPrefabs[randomPrefab], new Vector3(0, 0, 10), Quaternion.identity);
             yield return new WaitForSeconds(5);
         }
         while (Time.timeSinceLevelLoad > _levelTwoTime && Time.timeSinceLevelLoad <= _levelThreeTime)
         {
             int randomPrefab = Random.Range(6, 9);
             Instantiate(_levelPrefabs[randomPrefab], new Vector3(0, 0, 10), Quaternion.identity);
             yield return new WaitForSeconds(5);
         }
     }
 

I know this will make the script very long if i want to create more levels.

I would like to know if there is a way to instantiate prefabs within the time of their respective levels without having to use the while repetition system so often. ||| Thank you for your attention and patience.