RE: When would you use the Consumption vs Output vs Production Journal in Manufacturing?
If you are recording information on only one Production Order, than the Production Journal is likely the best place (albeit a bit clunky to get to). If your BOM is backflushed, you really only need the Output Journal, in which case it becomes the better option due to ease of access.
If you are recording information on multiple Production Orders, than the Consumption and Output Journals are likely the best place. As Inge pointed out, with the Cons. and Output Journals you can create multiple batches to allow people to record their information separate from other Users.
If everything is backflushed (BOM and Capacities), you don't need any of the Journals (assuming full output happens). Simply changing the Production Order to Finished can post the Output, Consumption, and Capacity Entries all at the same time. Just be aware this process is final and you cannot reopen the Production Order if you missed something.
In all cases, we recommend thorough process testing in a Sandbox before changing your live production processes.