I disagree with the premise that a shrimps diet is "consistent" in the wild. Firstly shrimp are opportunists in that they will eat anything they come across. Dead fish, dead insects, leaves, algae, detritus, pollen, fruits, ect. Secondly these foods will vary from season to season, and even over the space of days or weeks. For example, during times of floods/heavy rains, most of the leaves, moss, plants ect. are washed out of the system. I'd suggest the shrimp then rely on algae growth and detritus. Alternatively smaller rainfalls may wash lots of leaves into the system. Pollen and fruit are seasonal. Algae growth is somewhat seasonal too - higher growth in summer with warmer temperatures and longer day length. There are many more examples.
It's probably likely that most people provide a greater variety of food than is absolutely necessary to provide all the nutrients, vitamins and minerals that are required by shrimp. This is not a bad thing, but it's important not to get hung up on it and ignore other important factors that determine the health of our shrimp - water quality being the obvious example.