I tend to use the turntable a lot. It simply saves a lot of time. Instead of having to babysit the scanner while its doing a scan (Make a scan, move object, repeat), you can place the object on the table and tell it to make 50 scans and auto stitch it.
In most cases having 8 - 12 scans of a single object gives pretty good results, but more data tends to increase the quality of the scans. Especially the smarter smoothing algorithms that are used to filter out the high frequency noise of structured light scanners benefit from more data (at the obvious cost of memory & cpu cycles).