Once you've been in the consulting field for a reasonable amount of time, you'll be faced with a client that's in a bind and wants you to start immediately.
You'll scramble to adjust your schedule and make travel arrangements so that you can be on-site the very next Monday. You'll show up to the client site only to learn that they’ve not assigned you a workspace, nor have they set up your system access.
At this point, they will find "something" for you to do, so that you're not just sitting around. Being that they requested your presence on-site, and since you were onsite for 40 hours, they’re not going to have a problem approving your 40 hours for the week. They will do this even though you sat around, trying to stay busy the first two days, when you had no system access.