Honetly man.. I think the only people who could answer this question with any kind of accuracy would be the folks at GH... They probably have a team of scientists constantly testing different mixtures of food to see what has the best results at different stages of plant growth.. My guess would be that if they changed the feeding schedule a few years ago.. it was probably because their own research has been more finely tuned. I also know that since medicinal use came in a few years back.. many hydro food companies have been tailoring their formulas for cannabis (which are quite different from house plants). I think they just realized that the "house plant crowd" are NOT the ones buying their products.. and now that its actually legal to test for medical purposes.. many hydro food companies are taking advantage and tailoring their formulas specifically for cannabis.. Thats my best guess.. but maybe shoot them an email and get back to us just to be sure! lol