First, we'll start with Why we have crates. The Crates system was created as a way for newer characters to earn chyen while they seek out an official job, and then continue earning that little bit more with their poor paying Red Sector jobs while directly helping resupply NPC stores. We always have new characters coming so crates should be a fairly regular thing for them to be doing. Of course, we can find older character running crates as well to earn the little bit on the side, and there's nothing wrong with that either, after all, it helps restock the NPC stores.
Now for the policy about Crates.
The most asked question is how many crates you are allowed to take at the one time and the simple answer is one. You should only be taking one crate at a time. Dropping or stashing a crate to gain another is simply exploiting the way the code is intended to work and will be punished. The crates you are supplied with are heavy boxes full of supplies which you're not going to be able to put in your jacket/trouser pocket and walk around with. "Why don't you make them heavy code-wise?" Well, because then they would be too heavy for new characters to carry (Which is the main people that should be using Crates.)
The only exception to the one crate at a time rule is if your character has a tool to assist in transportation. For example, if you have a vehicle you may carry a crate from the provider and then store it in your vehicle, go back to the supplier, get another crate, store it in your vehicle and then deliver them to their intended drop-off locations. If you have a friend who is willing to help you, then you can collect a crate from the supplier, hand it to your friend to hold, then get another crate and go deliver them. This way, you're including another player in the process and creating some RP for them. Other than that, you are only permitted to take one crate at a time.
Hopefully, this helps clear up some confusion about crates, who should be mainly using them and how you should be using them. If you have any more questions then please, feel free to ask.