Well you can also upconvert Oneiromantic Revelations to Parabolan Parable and sell those during Maudlin Demand so surely it's more than once a year? :) With the Engineer, the next best need for this purpose after Correspondence Plaque is Palimpsest Scrap since you can buy it from the Rat-Market at +40% markup. In any case, there's no downside I can see and requires only a little extra effort so might as well do it if you're doing this grind.