Eh, that may be not entirely true! (said he quoting a line from Independence Day)......now David has no Area 51 (eh, except for some "non documented settings") but it sure as hell has a checkbox stating,
Align to previous scan......
on the bottom of the "Structure light" tab of the left menu.......now if that is checked David tries to allign scans automatically. I must admit, I have seen some not to pleasing results, so I rather scan by hand and I have no idea wether this takes into account the settings of the "Shape fusion" tab regarding prefered alligment method, but it is present in David.