I think my client described the problem best in an email to me:

(my client)
The problem is that when the job cost batch is retrieved in GL, it will be in the period of the invoice date, not the accounting date. So then I have to change the period again. This is relevant since the job cost related expenses flow to job cost for posting.

(me again)
I hope you see how this ends up defeating the purpose of using the Accounting Date for job-related invoices.

Steve