How to add to a rotation angle?

     public float m_MaxAngle;
 
     public float m_Speed;
 
     float m_TotalRotation;
 
     float m_NewAngle, m_CurrentAngle;
 
     void Update () 
     {
 
 
         transform.Rotate(-Vector3.forward, m_Speed * Time.deltaTime);
 
 
 
         m_NewAngle = Vector3.Angle(Vector3.up, transform.up);
         m_CurrentAngle = transform.rotation.z;
 
 
         m_TotalRotation = m_NewAngle - m_CurrentAngle;
         Debug.Log(m_TotalRotation);
     }

What I'm trying to do with this code is get the total rotation to add or subtract based on which way an object is rotating. If the object is rotating clockwise it's adding to m_TotalRotation, and counterclockwise it subtracts from m_TotalRotation. I want to be able to setup limits of how many times and object can rotate. The problem I am having difficulty understanding is why the variable m_TotalRotation stops increasing and starts deceasing when it reaches 180 degrees. I am also struggling with making subtract into the negatives when it hits 0. Here's an example I found, I'm trying to mimic something like this in 3D https://youtu.be/gE9Q9x4B5LA?t=131