It is important to get the setup of all the IT systems correct early in a project.
For example. If you have a team placed in a client office to do a project, they need to have good printing, internet, network drive access etc. Yet many projects in a client office are not given access to printing or similar and so must constantly email files to an administrator to print. This wastes a lot of time.
From personal experience, I have found that a combination of these restrictions to access can slow my work down by 50% or more.