How to rotate camera around object smoothly in fixed intervals

Basically I want the camera to rotate at 90 degree intervals upon keypress.

I have the following:

 public GameObject targetObject;
     private float targetAngle = 0;
     const float rotationAmount = 1.0f;
     
     // Update is called once per frame
     void Update()
     {
         
         // Trigger functions if Rotate is requested
         if (Input.GetKeyDown(KeyCode.LeftArrow)) {
             targetAngle -= 90.0f;
         } else if (Input.GetKeyDown(KeyCode.RightArrow)) {
             targetAngle += 90.0f;
         }
         
         if(targetAngle !=0)
         {
             Rotate();
         }
     }
     
     protected void Rotate()
     {
         
         if (targetAngle>0)
         {
             transform.RotateAround(targetObject.transform.position, Vector3.up, -rotationAmount);
             targetAngle -= rotationAmount;
         }
         else if(targetAngle <0)
         {
             transform.RotateAround(targetObject.transform.position, Vector3.up, rotationAmount);
             targetAngle += rotationAmount;
         }
 
     }
         

This works fine, but my question is should I be applying Time.Deltatime at any point to ensure it happens smoothly?

Thanks.