So what happens after you've take POF and forgotten about it, then get POF questions in Ops and/or Performance? Similarly for any other subject.
The progress tests are not supposed to be open book, they are there to ensure that you have actually learned something before you go on to the next stage.
And don't come up with the old bromide about never needing it in real life. It's getting boring. Ask the guys who have had navaids fail over Africa. You are supposed to be learning a trade.