One milestone that should be always be defined in a project from the control point of view is that Project Manager will notify the Client when the spend against budget reaches 80%. Doing an analysis about reasons that can make the project to be over budget at the end of the project.
One formal STOP for the project manager where s/he also have a milestone to see how things really go.
Sometimes the project manager is so busy in the weekly waves and have the hope that the time spent in the previous weeks is going to be recuperated.
I have worked in a project with this problem and one of the things makes me to detect the that the project was not going into the right direction was the ETC forecast was not always done in the right way, there were estimations that were clearly unrealistic.
Live is not perfect and there are so much projects that does not finish as you desire. This was one case more 🙁