Can't have two WaitForSeconds in one function?

I create a function like this:

 private IEnumerator Test(){
         //do something
         yield return new WaitForSeconds(0.3f);
        //don something
        yield return new WaitForSeconds(2.0f);
     }

it can't work. may i have to do it like this?

 private IEnumerator Test1(){
     //do something
     yield return new WaitForSeconds(1.0f);
 }
 
 private IEnumerator Test2(){
   StartCoroutine(Test1());
   yield return new WaitForSeconds(1.0f);
 }
 
 void Update(){
    StartCoroutine(Test2());
 }

this is a terrible solution