In response to your original question, variety is important, but not a science. As keepers, the goal is to replicate what the chameleon would experience in the wild; temperature ranges, humidity, light cycles, hydration, territory, climbing surfaces, breeding opportunities, and food sources.
Admittedly, we all probably don't replicate all of these, as some keepers don't breed the chameleon, and most keepers don't provide the size of a territory that most chameleons roam in the wild (although a free-range room is impressive!!).
With food we have some limitations, as we don't know what type of insects they are eating in each area they live in, but it is safe to say they definitely eat what insects they find.
That being said, it is reasonable that the research done on farmed insects for the reptile trade is applicable to chameleons. Farmed insects include crickets, super worms, meal worms, wax worms, black soldier fly larvae, housefly larvae, blue & green bottle fly larvae, and locust(locust in England).
Insects not farmed in large farm quantities, but still in the reptile food trade are springtails, isopods, aphids, rice flour beetles, bean beetles, cockroaches, horn worms, silkworms, stick insects, mantis, moths and butterflies.
In the 1990's we knew very little about chameleon nutrition, and we are miles ahead today on our understanding of vitamin A, Calcium, and Calcium/Phosphorus ratios. Even so, I fall back on the shotgun approach to feeding; If I can offer variety, I have a better chance of meeting a vitamin/calcium/protein need than 1 or 2 feeders could offer. I will probably never know what food or combination of foods were beneficial; as long as the chameleon is healthy my feeding program is working!
Your real source for food questions are the blogs by Sandrachamelon (look her up on the members list). We are fortunate to have someone with the depth she has on nutrition, check her blogs and threads out!
CHEERS!
Nick