Problem with initial calibration and alignment

I am using SkySafari 5 to calibrate my Celestron HD Edge with StarSense. After carring out the 3 step calibration, I use Goto on an object and fine tune the StarSense camera using the direction controls on the tablet. I then align and re-calibrate. Then I would have expected goto to put me back on the object I aligned with but its always off. Now I realised today that I never set the location and time in the tablet but as it was already defaulted to Current Location and Time then that should have been ok. Is that the case? Does the GPS on the tablet not define this?. Secondly. How many objects should I align on. All of the guides I have read suggest one, But  friend suggested that I should choose three?. Is that correct. If I should only do one then why does it not pick up the original go to object exactly.