The counter point to how carlos is doing it is a simple view of variety is the spice of life.
Take humans for example. We have a few basic nutritional needs in order for us to be healthy, but adding a variety to our diets makes a "healthier" if you will.
What I am meaning to say is that doing a rotation of several supplements along with a variety of foods will theoretically provide your pets with a healthier nutritional balance.
I saw all this with no real preference one way or the other. I have been toying with the idea myself to switch to a single daily supplement with Vit A mixed in 2 times a month simply because I currenty buy 4 differnet supplements that I have to throw out every 6 months and replace. It would be cheaper to buy only one, but I have not made a decision yet. Some people (who I respect their opinions and advice greatly) are on the Multiple supplement and varied diet side of this conversation and that tends to keep me leaning that way, but then I have friends like Carlos who I also respect a great deal on the single supplement side of the conversation.
I am not a scientist and can not offer proof one way or the other. What I can offer as advice is to try one way. See how your frogs act and then try the other way. Find out what you feel is benefiting your frogs the best and stick with it.
Paul