I've done two diesel purges on my 84 300D NA in two years using diesel purge in the plastic bottle under the hood method. I noticed no difference but it did give me piece of mind. Since you have been using Stanadyne (IMO the best diesel fuel additive) in every tank you are keeping your fuel system/injectors clean. I have a '97 Powerstroke F-350 with 326K miles that has had Stanadyne in every tank since 2002. My injectors are original and are clean as a whistle. Stick with what you have been doing. Your injectors will love you forever.
