Class for servo

Dear friends I created a Class for servo to turn servo from pos 90 to 150 degrees "left".

I would like it goes back to 90 after 6 seconds.

Could you advise me a method?

#include    <Servo.h>     

  class ServoClass
{
        Servo serv;    
                      
        int servPosition;   
        int interval;
unsigned long lastTimeCheck;  
public:
ServoClass ()
{
  interval=60;
  servPosition=0;
lastTimeCheck=millis(); 
}
void AttachServo (int pin)
{
        serv.attach(pin);     
        servPosition= 90;         
        serv.write(servPosition);   
}
void Update ()
{
        if (servPosition<150)
        {
                if ((millis() - lastTimeCheck)>= interval)     
                                                                      
                                                                 
                {
                servPosition++;                
                serv.write(servPosition);          
                lastTimeCheck= millis();  
                }
        }
}
};  
                
     
ServoClass serv1;    
                       
void setup() 
{
        serv1.AttachServo(9);          
                                    
}
void loop() 
{
        serv1.Update();

}

What is the problem? There may, or may not, be something to do when the Update() method is called. What to do may involve moving the servo clockwise, twiddling your thumbs, or moving the servo counterclockwise.

Frankly, I can't see the benefit of a class for this.