How long did it take FDR to sign the letters of the 19,000 Americans killed in the Battle of the Bulge in 1944? Had he yet finished signing letters for those killed at Pearl Harbor, Guadacanal, Bataan, Slapton Sands, Omaha Beach, etc., etc.?
Signing 1,300 letters over 18 months is a little different than 200-300 per day during WWII.