Hi Jobi, its not all that complicated. When I began, I used all sorts of prey items. All the commonly available and lots of wild critters, like lizards and grasshoppers.
As I progressed successfully, I could test a prey item easily. For instance, if I fed five types of prey items, I could simply remove one and see if progress changes. If the monitors progress is not hindered, then that prey item most likely is not adding anything.
When I stopped feeding mealworns, there was no negative effect what so ever. When I stopped feeding crickets, there was a tremendous negative effect. When I removed lizards, there was a slight negative effect. Then I added mice parts or pinkies, and the progress was regained. When I stopped feeding mice, there was little negative effects. I never fed roaches, I attempted too at one time, but my monitors would not eat them, so out they went. I did not have problems so there was no need to force roaches.
The point is, I based all decisions of a set level of success. Not on theory. That level was simple, small monitors should reach maturity in under a year and larger monitors in under 18 months and both should sucessfully multiclutch. Those goals were very average in actual practice, all monitors could and did far exceed "plan".
As you know, when I stopped buying crickets, my small monitor production dropped like a stone. They did not meet that level of success until I learned to manage crickets again.
I think most people overdo most things and crickets are no different. They simply do to much. They provide a varied diet, veggies, and this and that. Much like people do with monitors. People tend to base their approach on theory and not result. They also base it on, what they are told and not actual experience. In all cases I based my approach on results. You must have some faith and not have to "understand" all things. If it works then it works. Its all about that simple.
In my experience the less I do with crickets the better they do. I use grounded up dogfood mixed with laying mash. I am positive I could eliminate the mash and the crickets would do great. I give them a choice of temps and a substrate of dirt(any stinking kind of dirt will do)
I have been told of all sorts of things that could happen like bigger crickets eating the smaller crickets and such. That never came to pass. They will only eat eachother if starved to death. Again like monitors. People should really understand that animals have levels of hunger and do not go by YOUR(keepers) schedules. Again simply put, they only eat eachother if forced too.
I understand why people feed on schedules, but those keepers should not complain if their charges eat eachother because the schedules do not offer enough food. Sorry for ranting, cheers