I am a crafter, but lately I have been mostly gathering for other people, and thus comes my viewpoint...
For me, or anyone else to actually play and gather simultaneously, and subsequently supply others with what we gather in response to your requests, it would help if you asked for less total items at one time.
What I'm saying is, that if you want 100 silk cloth, rather than ask for 100 silk cloth, ask for 5 different stacks of 20 silk cloth.
Then, one person isn't out grinding to get 100 silk to fill your order. Five people who are questing in the areas that drop silk, and who happen to have 20 in their bags to spare, can easily fill your order.
You spend the same resources to request... Nobody else is grinding... You probably actually get your order filled faster... There are a lot of pros to this equation rather than cons.
In the end, this is just my suggestion, since I'm actually 'trying' every morning to fill at least one, if not numerous orders for everyone, putting my own love of crafting aside to help out because I know people need it.
I hope this helps you get your orders filled faster. Thanks.