Coroutines Madness ();

Hello folks, I've come with coroutines madness:

First Question is Understanding WHY the MainCheckRoutine() is executed twice......

 private bool ready;
       private float customTime; 
     
      void Awake()
         {
                    ready = false;
                 }
     void  Start () {       
             customTime = 0.8f;
             StartCoroutine( ELbuscon());
                       }
     
     void Update()
         {
             customTime -= Time.deltaTime;
             if (customTime < 0)
             {
                 if (ready == false)
                 {
                     GameObject[] fs = GameObject.FindGameObjectsWithTag("litrick");
                     GameObject[] ts = GameObject.FindGameObjectsWithTag("estrello");
                     GameObject[] rs = GameObject.FindGameObjectsWithTag("match");
     
                     if (fs.Length > 0 || ts.Length > 0 || rs.Length >0)
                     {
                                                 //nothing
                     }
                     else
                     {
                       ready = true;
                     }
                 }
             }
         }
     
     IEnumerator ELbuscon()
         {
             while(ready == false)
             {
                 yield return new WaitForFixedUpdate();
                }
            
                 MainCheckRoutine();
         }
     void MainCheckRoutine(){
     Debug.Log("why am i exectude twice?"); 
 SomeCheckingThingFunc();
 FinalStep();
     }
 void FinalStep(){
 if(something==else){
 StartCoroutine(Elbuscon());}
 // THIS Freezes out everything
 }

The fact is that if i swtich Start function to IEnumerator Start(){}. and i make some yield inside.... the code just runs once....... makes no sense on me because even Coroutines play independient its supose to yield the instructions after ready = true is met....... Just once becouse Start is fired once... dont understand yah! :(_

Second Question is about looping and freezing. Which would be the best approach to loop the Elbuscon() function after a requirements on the very end of this fucntion; like FinalStep(); this way seems to freeze unityeditor couse a infinite loop even it's not.(my guess...)

Thank You !