The Crititcal Path Methodology is correct. However, if you have a constraint such as “Must start on” or Start No Later Than…. it will over-ride the calculation. Also , if a task is moved …. it creates and Actual Start. A lot of people move a task and the actual start will anchor the task regardless of the precedence relationships.
That is the same on the Cloud AI version but we have re-written the algorithm and it is more efficient but calculates the same…