Rotating the scan will not produce as clean a scan as the original. Try a side by side comparison between an origial scan and one that has been digitally rotated. There is always loss of definition. Spend the extra time.

On my thousands of scans I probably averaged 2.5 to 3 scans per chip until I got it right.

I was told of an ivory collector who went to Staples and bought a green board (color of poker felt) and glued the chips to the board before scanning. The glue was of a type where the chips could be removed without damage. The glue could then be reused for the next set of chips.