I usually only offer probiotics around antibiotic treatments or if their GI system is showing issues. Once things return to normal I discontinue use and just stick with calcium and multivitamin supplements on bugs. I don't think offering probiotics will be harmful, just not necessary and possibly wasteful as Kingofnobbys suggested. You also want to be careful about which probiotic you're offering. If the label shows it has Enterococcus, I would choose a different option. It is not harmful to dragons but can be harmful to humans so if you come in contact with it or with poop that has it, it has a potential to make you sick if you don't wash your hands thoroughly.