Moveit RobotTrajectory time_from_start not correct

edit

Hello,

I want to find out for how long my robot will be moving on a cartesian path. For that I plan the path between two waypoints with:

(plan, fraction) = self.move_group.compute_cartesian_path(pose_waypoints, self.eef_step, self.jump_threshold)

and then look into plan by doing:

duration_in_sec = plan.joint_trajectory.points[-1].time_from_start.nsecs / 1000000

The problem is that the duration I get is wrong. I do this multiple times for multiple waypoints and add the durations together. Something of about 30 seconds comes out, but the robot needs more than 100 seconds in this example. What am I doing wrong?

Thanks for your help, ask me anything if something is unclear.