Currently, we usually limit our scanning to about 1 slide tray per semester. As to the labeling, we are not the content expert, so labeling would not only be time consuming, but error prone. Our process is to have the scans are organized in a folder corresponding to the slide tray (e.g., "Tray 5" or "Egypt 18th Dynasty"). Slides are auto-numbered (e.g., Tray5-18.tiff--i.e., the 18th slide in Tray Five). We add no other metadata.