Being originally from Louisiana (28 years) and having a ton of gumbo recipes, I had to go and get out the cookbooks for a little comparison.

One recipe, after making the Gumbo, states "Serve over rice with a dash of file" (1/8 tsp?)

Another states now this is for a "crowd" recipe with 10 lbs of shrimp and 6 lbs of dark crab meat with 8 lbs of okra, etc... states 8 tbsp of file. This recipe states that it makes 12 gallons.

So, if you eat a "gallon" of the latter gumbo, you are eating .666 of a tbsp of the file.