Usually supplements have recommendations for a reason, therefore this decision would depend on the supplement you have chosen and what additional ingredients are inside the supplement. For example, many Fish Oil supplements or Omega 3 supplements also contain Vitamin E. Therefore the reason these supplements may only recommend you take one capsule is because you'll go over the RDA for Vitamin E if you took anymore. Not to mention the fact that you would have to consider how much Vitamin E you consume through your diet as well! However, if you want to embrace the FULL hair benefits from Omega-3, which almost entirely come from the EPA and DHA, you'll need to try to hit 700mg and 300mg respectively, either by choosing a supplement that can help you hit this goal, or by making different choices within your diet (e.g. eating more fish).