Is a daily dose of 500 milligrams of a magnesium blend supplement considered excessive, and what are the potential risks or benefits of this dosage?

No, It's not too much. Just make sure also that you're taking the other minerals too, because they all work together, especially with potassium, magnesium, calcium, magnesium, but I wouldn't take any calcium.You can normally get that from the diet. So I think also vitamin D is important with magnesium. They both need each other for, for optimum function.