Dylan O’Donnell recently had a video on his channel regarding the Synscan Polar Alignment routine.
He demonstrated a brief basic procedure ( the presentation was a bit fragmented but gave a general idea how it works )
https://m.youtube.com/watch?v=hAK05cFsJIc
I’ve found there’s a few prerequisites in achieving tighter polar alignment with Synscan like the location of your selected polar alignment Star and turning off the Star Alignment Filter , using your capture software alignment screen with reticle and zoom feature so your PA Star is not a dot on your screen but a larger target for centering operations etc….
In most cases 2 to 3 iterations are required to achieve arc minute PA but this is dependent on sky conditions and the PA Star location. In some cases I’ve had to perform 3 to 5 iterations to achieve good PA
Folk who buy second hand Skywatcher mounts probably don’t receive a Synscan manual with it so generally wouldn’t know about this inbuilt PA feature on the HC
Cheers