It is good practice to run the cost adjustment automatically when you post because unit costs are more frequently updated and therefore more accurate. The disadvantage is that the performance of the database can be affected by running the cost adjustment so often.
Because it is important to keep the unit cost of an item up to date, it is recommend that you run the Adjust Cost - Item Entries batch job as often as possible, during nonworking hours. Alternatively, use automatic cost adjustment. This ensures that the unit cost is updated for items daily.
Regardless if you run the cost adjustment manually or automatically, the adjustment process and its consequences are the same. Microsoft Dynamics NAV calculates the value of the inbound transaction and forwards that cost to any outbound transactions, such as sales or consumptions, which have been applied to the inbound transaction. The cost adjustment creates value entries that contain adjustment amounts and amounts that compensate for rounding.
The new adjustment and rounding value entries have the posting date of the related invoice. Exceptions are if the value entries fall in a closed accounting period or inventory period or if the posting date is earlier than the date in the Allow Posting From field in the General Ledger Setup window. If this occurs, the batch job assigns the posting date as the first date of the next open period.