We use several indirect WO's every month to collect various expensed jobs such as shop equipment that we make and R&D.  The class code for the parts we use is set to use the expense account for WIP and for the asset account.  As we issue materials and labor the WIP (expense) account is debited which collects the cost for the month.  When the WO is finished, the GL transaction is net $0 to the asset account.  Generally speaking we close these work orders at the end of every month, but sometimes the project may span a couple of months in which case the expenses  are captured in the month they happen.  
 
This is why the ability to exclude "I" types from the WIP report is important.  These costs are not going to our regular WIP account and if they show up (sometimes the person who creates them forgets to make them "I") the WIP report does not match the WIP GL account.
 
We are happy with the way this is working, except for the fact that once you close "I" type WO's they will be listed in the WIP report if you are looking at "C" closed work orders also.