I just did some experimenting and wrote what often worked for me. It is not a scientifically arrived at figure. I originally used it before I discovered Nutri Bac. GSE seems to work sort of like a broad antibiotic. It has even proven effective against fungus and I believe, some viruses, as well as bacteria and microbes in general. There has been quite a bit written about it in agricultural uses - you can probably find info through Google.
Now, I usually start with a round of GSE for the first week or two when starting a regurge treatment, along with Nutri Bac and the nursing care outlined in my FAQ. (I also often use it as a general disinfectant in drinking water, since I can't change water bowls everyday). Then I discontinue the GSE while continuing the NB. That is because I don't know if the GSE could have a negative effect on the NB "good" microbes that are trying to become established in the digestive tract. I don't know if anyone has the answer to that. So I do it the way I do because it seems logical, conservative, and has often worked.
Unfortunately, herpetoculture is new enough that even herp vets often don't have the "for - sure" answers that we would like. Much of any breeder's advice comes from anecdotal trial and error experience that has often worked for us in the past. But of course we have to be open-minded enough to always watch for new methods that will work better (but not SO open minded that our brains fall out, lol!) We have to use our best judgment, based on our own and other people's experience, along with whatever scientific discoveries come along to help advance our hobby and give us new products to try out.