The TF-4 bottle says the stock solution should not be kept longer than 1 year, I would assume that is for a full bottle. I have a note written on my bottle that the 1:3 working solution can be kept in a full bottle for 6 months. For film, I usually mix 16oz at a time, since that's the size of bottles I have. For prints, I mix a half gallon, that's a good amount for 12x16 trays.