In order to determine your delay time (the time it takes to travel down the slider), you must fill out a few fields. Currently these fields include slider type, motor type, distance, pulse mode, timelapse duration, weight of the camera rig and angle of the setup.
The estimator is within +/- 10% of your desired time. That basically means that if you are doing a two hour timelapse, the move will finish within +/- 20 minutes of your desired end point.
***If you happen to go past the end of the slider, you will not wreck anything. The slider is based on a clutch system and because there are only small bursts of power are being sent to the motor, it is unable to push enough power to advance it beyond the end point.