Going on memory here, but I seem to remember series of papers by Burfield and Smithers in the 1970s-1980s comparing various desiccants and various solvents. One of the papers was a reconsideration of Dri-Rite after someone from the company objected to their heating of commercial Dri-Rite. Maybe the authors were over-drying it. If anyone is interested, I'll go through what I have.
EDT
"Desiccant Efficiency in Solvent and Reagent Drying 9. A Reassessment of Calcium Sulfate as a Drying Agent:" David R. Burfield. JOC !984 49, 3852.